One Assault, one Heavy, one Medium, one light.
I’m old school. I don’t really use Battle Value or other point systems. We tend to just use weight, like-for-like. If you have two heavies and two medium mechs, then so do I.
I know what you’re actually asking. You want specific chassis and variants. I’ll be honest here as well. Whichever mech looks the coolest. Thankfully, the newest art has FINALLY done a lot of mechs justice (I’ve been playing since 1986).
Is that shallow? Yup! Do we care? Nope! We run what we like, not what’s good. Within reason. I won’t run the original Banshee with the 4/6 speed, with only an AC-5 and a PPC. But the newest standard is the Banshee-S that moves 3/5, and is decked out like a proper assault mech weaponry.
But the normal lance setup is one mech from each weight class.