I'm not familiar with SAS (I have the d20 conversion, but have no idea what the Tri-Stat rules looked like).
But M&M2E I'd heartily recommend. The
Atomic Think Tank forums have a Roll Call section that has, literally *thousands* of characters statted up, by fans who really get the system. When I was writing up some Nightcrawler knock-offs for a scenario, I did a search on Nightcrawler in that section and found five different versions of him that I could look at for inspiration and design techniques to rip off for my own stuff.
Obscure X-characters like the Acolytes and Morlocks have even been statted up by some, so that if you want to throw familiar faces at players who are familiar with the X-verse, you've got that option, and if a player says, "I want to play someone who has powers like Magik," there will be several choices for you to look at for designing that sort of power.
I was a big fan of 1st edition M&M, and really struggled to 'get' the changes in 2E, but several people there sort of took me in hand and showed me how to convert some ideas and stat them out in 2E, and since then, I like it even more than 1st edition!
Generally, the concept of 'power level' and 'trade-offs' makes it relatively painless to make a team with a 'Superman' and a 'Batman' character on it, and keep them at least somewhat balanced.
In a standard four-color game, everyone will be Power Level 10. Normally, a Power Level 10 character can't have more than a +10 attack, +10 damage, +10 defense and +10 toughness. Using 'trade-offs,' a character can still be considered to fit into power level 10, but swap some attack for damage, or some defense for toughness.
A more 'Hulk' like character, easy to hit and not that accurate, but nearly impervious to harm and hitting like the train that delivered the mack truck, could have a +5 attack, +15 damage, +5 defense, +15 toughness.
Someone like Spiderman or Batman or Deathstroke the Terminator might be insanely accurate and hard to hit, but not be ridiculously strong. Give one of them a +15 to hit but only a +5 damage, and a +15 defense but only +5 toughness, and they still count as effectively power level 10, since they'll have weak areas to counter their strong areas.
(And, naturally, feats like Power Attack, which takes an attack penalty for a damage bonus, just as it does in D&D, might allow the Deathstroke character to make up for his weaker punches by sacrificing some of his amazing accuracy, making some characters extremely flexible. There are also tradeoff feats called Accurate Attack (+atk, -dam), All-Out Attack (+atk, -def) and Defensive Attack (+def, -atk, like Combat Expertise), creating a lot of potential flexibility, for those who are interested in that sort of thing.)
