Designs that cause headaches?
3025: Firestarter FS9-H. A mech that deals more heat to itself than to the enemy must be something. Best range? Close combat, but it does not have the armor to slug it out and to make things even worse there is a ton of MG ammo inside the right side. In a direct confrontation against other mechs and without fire rules active (usual situation on most tables) it has little to offer.
3050: There are so many weird redesigns and introductions I don't know where to start. Hornet -171, Falcon -4P (hardly no firepower, suboptimal movement), Assassin -23 (scouting yes, but little less), Enforcer -5D (hot like hell what could have been prevented with a little more optimization), Hunchback -5M (bumm, bumm, bumm ... where is my ammo?), Hoplite -4D (oversinked, slow, mediocre weaponry. Even a Panther could bring the same damage to bear.), Jagermech -DD (still no armor, useless medium pulse lasers as it should stay away from any direct confrontation, now with fragile XL engine), Mauler -1R (well, long range and thus not totally flawed with its thin armor, but basicly limited to those four AC ping and twin LRMs), Annihilator -2A (no real movement, thin armor for 100 tons and still those damn medium pulse lasers). But my candidate for WTF is the Quickdraw -5M. Mediocre armor despite the fact it is made of ferrofibrit, a one-shot SRM 4 instead of a reloading model, CASE is not bad, but now only for a single ton of ammo, but 13 double heat sinks for effectivly two M-lasers, a LRM 10 and jumping heat... err what?
3055: Another case of screwed designs thanks to the new-tech-syndrom. Dart -3S (3 small pulse lasers in cavernous frame ... no firepower, no range, no armor and so many possibilities left out), Jackal -1532 (heat sinks? But two tons of ammo while missing CASE (and, as we are talking about it, one ton in the CT)), Hollander (weird design, low armor level, no secondary armament), Snake -1V (massivly oversinked, mediocre armor, questionable damage output, XL engine but three tons of ammo), Huron Warrior (Liaos answer to the Enforcer? Same mistakes as the -5D), Apollo -1M (not bad, but could be even better with some minor changes), Albatross -3U (not totally bad, but tons of ammo but only 13 tons of armor), Berserker -B3 (why twin LRM 10s in a brawler mech?), Goshawk (hope you can close in soon...), but my nomination goes to the War Dog -02FC. Two one-shot Streak-SRM 2 in the legs. Why? Both one-shot mali add up to one ton of ammo for both launchers. Insane 40 shots of gauss ammo. Two tons of AMS ammo (maybe a result of the old AMS rules). A whole lot of short range weapons but only a single gauss for a long time. The asymmetric armor is more of a design gag than a real help. My best guess: this mech was designed as a 70-ton chassis and upgraded to 75 tons afterwards.
3058: Maybe the TRO with the most optimized mechs of all, but still with models that could need a review. Owens Omni (too much electronic hardwired, single heat sinks. Massivly limited pod space), Strider Omni (nice base, but why single heat sinks? Mostly limited to missile based load outs), Linebacker -LH2, Merlin -1A, Striker -2C and -2S (only acceptable as low cost militia mech as it could be produced during the third succession war as well), Piranha (not really bad if it can make it into your six, but unless it is there it is just a poor target), Hunchback IIc (intended as suicid mech ... has to be played as such), Crossbow (16 tons of pod space on a 65 ton clan chassis ... well there could be truly more available if the designers opted for at least a little bit more advanced clan tech). But the Bushwacker beats them all. An AC 10 while everyone else uses a LB 10-X, machine guns while anything else is long range based, ferrofibrous armor while an endosteel frame could have saved the weight for better LRMs or armor or whatever.
3060: Not that many misdesigns. Garm -01A (poorly armored, mediocre long range weaponry, has to be kept out of the worst fighting), Initiate -02 (tons of short range weapons but poor mobility), Bishamon -4K (C3-master computer in an extreme short range chassis. Your enemy loves you for this shitty design as it is forced into ECM bubbles or heavy weapons fire), Cobra -02 (no CASE, entire ammo on one side with nothing else as crit sponge, bad armor and mediocre mobility), Marshal -X1 (a bit of everything, but not enough of something special), Yeoman -6Y (even worse than the Cobra. Superspecialised LRM boat. No secondary armament, badly armored. Boarder camper par exellence), Urbanmech IIc (still a trashcan, even with clantech upgrades), Canis (burning hot, slow). But the Black Watch -7R causes me the most headaches. Only three ammodepending weapons and almost all of them carry only limited quantities of ammunition. This mech really needs a C3-network, but unfortunately it costs a lot of BV.
3067: Return of the new tech syndrom, but it could be worse. Anubis -3L (nice little supporter, but only 6 shots for each of its 4 LRMs. Afterwards it is reduced to a single ER small laser - reducing the effectivness of stealth armor to no secondary target), Stiletto -4A (-4B already shows what it should be), Blue Flame -21 (cooking on low heat...), Thanatos -4S (a 75 ton mech with the firepower of medium. Biggest eyesore is that MRM 20. Exchange for a LRM 15 could repair many problems of this mech), Solitaire (too many heavy lasers to be good), Pinion (no need for a heavy large laser nor the micro pulse lasers), Hellfire, Burrock (good for maniacs but otherwise a little bit too much heavy lasers). Nevertheless the Uziel -3S tops them all by a large margin. This useless PoS must have been designed by someone who truly hates the LA. With a decent -2S design presented in Mechwarrior 4 and also included into the record sheets noone really understands why this decrepit bullshit should be the standard production model. An LB 2-X with a single ton of ammo (no chance to change, so usually cluster only) as your only long range weapon and a buttload of short range weapons while your armor is mediocre at best. Yeah ... no.
(Dis-)honorable mention: The Fafnir -4A. Bullshit as an Archons personal ride. I don't know who designed but this trash still infuriates me.
3075: With the Jihad, the dark age designs were introduced and thus the horror started again. Legionnaire -2D (mostly because of different rules for the use of targeting computers, the Legionnaire lost a lot of its original appeal), Defiance -3S (overheating, tons of questionable weapons, cost increasing but relatively useless TSMs. The more simple -3T is the better choice), Balius (a quad omni ... really?), Jupiter (why 4 UAC 5s? Was there no better way to use that weight?), Jackrabbit (no energy weapon on a light chassis, 6 points of damage maximum, hardly no armor), Von Rohrs /Hebi (a heavier, not-jump capable Griffin), Ymir -2B (badly armored, tons of small weapons), Phoenix -3R (questionable armament). But nothing beats the Ryoken II. No energy based back-up, and badly low on missiles. After 8 salvos, this clanmade mech is reduced to 4 LB 2-X. Err... no thanks (and to make things even worse: the BV is no incentive at all).
3085: This TRO delivered some extremly optimized designs and some ... more than just questionable. Mjolnir (This thing was only designed to smash an enemies head with a single melee attack. Problems: keeping the TSM heated up needs permanent readusting of your heat sinks, mace has a bad to hit number and a good chance to floor your own mech), Eisenfaust (bad mobility mostly because of useless medium pulse lasers), Brahma (i still don't get it what this mech is used for), Shen Yi (why MRMs? Why not two LRM 15 and everything is OK), Gallant -7-0 (no range, permant jumping), Mangonel -3L (not to be mistaken with the -3W, which is a clantech monster. This one is badly armored and low on ammo), Peacekeeper -1A (horrifing expensive, with almost large weapons only it is complicated to keep the heat level of the TSM), Trebaruna -XB (did it really need iJJs? 20 tons of weight burried what 6 tons could almost do as well), Pack Hunter II (badly armored thanks to B-pods), Dasher II (no words...), Goshawk II (no replacement for the old Goshawk), Kuma (weapons? This is a 60 ton clanmech!).
And then there is the Targe. Anemic damage output, mediocre armor (even with heavy ferrofibrous armor) or the -2N with two tons of ammo placed in the legs while utilizing a MASC. If everything goes wrong, this mech destroys itself without being hit even once.
3150: And again new-tech syndrom at its ... worst. Prey seeker (it takes a ton of high tech to mount two upgraded medium lasers), Antlion (reinforced frame but XL engine, highly inaccurate mech mortars and not much more), Götterdämmerung (Compact engine and gyro burn through a lot of tonnage for a questionable increase in stability), Hawkwolf (nice idea, but low tech ruins it, no energy back-up), Stalker II (depends highly on an absolute elite pilot (not gunner) to get its medium lasers to the enemy), King Crab -009 (bullshit weapons loadout, especially those light AC 5, could need an entire weapons refit).
But the Storm Raider is the abysmal PoS of the time. I can't find a single variant of this mech that appeals to me. Almost no ranged firepower in any model, no energy back-up, mace instead of hatchet (worsened to hit chance and a chance to floor yourself), XL engines and questionable armor layout in several variants.
So to sum it up:
Although there are always variants and models with questionable design quirks, there is always one with more flaws than any other.
3025: Firestarter FS9-H
3050: Quickdraw -5M
3055: War Dog -02FC
3058: Bushwacker -X1
3060: Black Watch -7R
3067: Uziel -3S
3075: Ryoken II
3085: Targe (-1N as well as the -2N)
3150: Storm Raider (any variant)
Sorry for the really long post.