I think second edition is the best because of simplicity. There are enough rules as it is. Third edition was a nightmare!
They all had their quirks and their strongpoints.
I agree that MW2E strong point was simplicity.
It allowed for quick creation of characters that spent most their time in the mechs but could still do some "roleplay" outside them.
It is also a nice option for fleshing out Unit NPCs w/o getting into the massive creation point & tables of 1E or 3E
We used MW2E as the basis for a Clan Wolf campaign and I admit to absolutely tweeking Rexor to being a God in the mech since most of it was BT playing, but outside it he was average at best, mostly below average.
Third had it's issues, but my group ran into the problem of mechwarriors being good inside the machine but not so great out side with 2nd. AToW is a better fit for what my group wants, my GM for AToW rants and raves that it's everything he wanted. I just feel that we can do a campaign without house rules now.
That was our issue, but frankly we wanted it that way, the MW2E part was an extention of the main BT play.
MW2E made for some very limited skill selections but it had the nice method of "untrained" default rolling for worst 2 of 3 that you could use for just about anything.
Royalty and Rogues
Bloodright
Null Set
Living Legends
The Black Thorns(?)
To those I would add the Falcon & Wolf IIRC as well as all the Field Manuals.
Not really, we went with the archtypes for the first 2nd ed. game. We could handle ourselves outside of a mech. Just not to the degree we wanted. The last game we did with 2nd, the GM gave us extra points to buy additional skills. Everyone was much happier with that game. Learned to love the gyroslug rifle in that one.
I found that after you covered the "basic-2" of P/G it was best to just buy as many L1 skills as you could to avoid the "untrained" option and to go w/ the best Attributes you could at creation for lower #s from the start.