I got in on the LB10 band wagon. I think it is clear why, in a list with no GR, PPC or ML it would be the king. Its actualy lighter than its predecessor, with more range, less heat, and some specal bonuses for cluster ammo. Yes, with DHS I'd tend to have a PPC or ER PPC for sheer damage over it, but the ability to crit seek and to work over air and armor units makes it a great companion to the PPC or ER PPC, or to the GR.
I also picked the LRM (15), which is really a lovely ranged weapon, with a fun mix of crits and damage clusters with its five pointers. Clan LRMs of course are almost too good to be belived, but IS LRMs are eminantly usable, even in the GR era. And again, they pair with PPCs and MLs extreemly nicely, with the ML covering the minimum almost perfictly, and the PPC or GR adding ranged hole punching.
I'd probably pick the SRM or MML after that. I don't really perfer the MML most of the time, since I tend to like more specalized mechs, but on some big slow mechs, or mixed in on bodyguard type support mechs, they can shine. Part of it two is my LRM bias; they're more closely on par with SRMs, so using them on a mech intended to be an infighter is less of a loss than using them on a mech indended as a support unit, and being able to shoot yourself in can be nice.
Probably some sort of pulse after that. I'd probably go medium in either Clan or IS, but the Clan LPL is really majestic. With the mediums, they're just light enough to serve as secondaries behind your LRMs or PPCs or GRs or LLs to keep mechs from closing, and you can still mount them on faster scout hunters, or on brawlers behind their SRMs. The IS LPL is somewhat problematic, though hardly worthless,