Archer-2S and Ostsol-4D.
The former has two LRM-15’s with two tons ammo each, two SRM-4’s with a ton of ammo each, 4 medium lasers and nearly max armor. It’s deadly at any range for extended periods.
The latter is somewhat lacking in armor, but mostly in its arms, which are there to absorb fire and make punch attacks. It has two large lasers, four medium lasers and a 5/8 speed.
Also, since you said for the BV, let’s look to the Quickdraw in both 4G and 5A models, and Rifleman in 3N and 3C models.
The former in its 4G model can hit at most ranges, and is excellently fast and mobile. The 5A model loses the long range ability, but gains a lot up close.
The latter has to be very careful of its heat, is only averagely fast for a heavy, and also lacks armor, but can hit very hard when it counts.
Both ‘Mechs in both models are cheaper in BV than most other heavies, meaning in an equal BV play, you can have a better MechWarrior than your opponent if they choose a more typical ‘Mech.
Ruger