Mech The Thunderbolt. It's tough, easy to modify, and almost everyone makes them. Spare parts are easy to come by, and you could get the plans for the 7M which uses basic Star Leauge tech (DHS, Ferro, CASE, ER Large Laser, Streak 2) from Marik on the cheap. It will do just about any role other then cavalry, and that can also be added with jump jets. Kick in Endo Steel for the 5rb Royal variant as a command unit, and you have a solid long amd short range trooper for any duty.
The TDR-7M is certainly a solid design, but high-tech enough that I wonder how easy it would be to get the tooling needed. Amusingly enough, though, the MUL lists it as being in use by mercenaries, the Marian Hegemony and the Magistracy as of the Dark Age era.
Amusingly, a vehicle that ends up pairing better with it due to the engine is the Patton, but if you can produce the Patton, do you really need the Thunderbolt?
Aerospace fighter the Stingray. Also made by the friendly neighborhood purple eagle, the Stingray is an all energy weapons 60 ton fighter designed for dogfighting and strafing. It has several variants, is easy to support, and can be used as an all around generalist like the Thunderbolt. The Stingray moves 6/9 and has 11.5 tons of armor. You get a PPC, two larg3 lasers and two mediums. It's not flashy, but it's solid like the Thunderbolt
Stingray's a solid design. No disagreements there, other than there's not much parts synergy between the Thud and the Stingray.
With that said...where there is parts synergy with the Stingray is the Schrek PPC Carrier. That uses the same engine, fits PPCs as its main gun, and would be a solid replacement for the Burke: it loses a bit of ranged damage compared to the Burke, but is faster and more durable.
For a 'Mech to use instead of the Thunderbolt, then, you've got the option of a medium trooper in the form of the Sentinel (3KA and 3KB sport a LL or PPC, respectively), or mass-producing the CLNT-2-3T Clint Denton (with its LL). The LNC25-02 Lancelot downgrade uses the same basic weapons, too.
Vehicle-Assuming you want a core tank, I would go with the Bulldog. It's 60 tons, with an ICE, 2 SRM-4s and a Large Laser. The Bulldog moves 4/6, mounts 6.5 tons of armor, and is cheap at 606 BV. The Manticote may have more powerful weapons, amd the Goblin carries infantry, but the Bulldog keeps on coming. It has all sorts of weapons swaps from LB-5s to ER Large Lasers, and the Fuel Cell mod makes it tough enough for line or garrison duty.
The Manticore, OTOH, is based around a PPC and a 240-rating fusion engine, same as the Stingray, so it's got that going for it. You're right though that there are a ton of variants for the Bulldog. It just always weirds me out to see ICE-powered vehicles based around a large energy weapon for their main gun.
Like we previously discussed, I think the Goblin is the best choice for Niops... lots of variants, and can fit in a light cubicle.
I know the Goblin has at least one fusion version, fitted with an LPL as the main gun IIRC.
For both the Bulldog and the main production runs of the Goblin, given they're ICE vehicles (as are most of the standard APCs), I wonder how well that would work on the worlds in the Niops system. We don't know about Niops V and VI, but the most advanced life forms on Niops VII are fish analogues, implying there wasn't much in the way of terrestrial lifeforms, which means you may also not have had the extensive plant biomass on land that would result in natural petroleum deposits. With that said, if you've got enough methane, it doesn't matter, I suppose, and I suspect there are enough tidal forces on Niops V, VI and VII to keep them geogically-active, which might help as well.
