Since you did say you were open to Non-d20 suggestions, I will take this opportunity to plug Basic Action Super Heroes, aka, BASH!
It is a very simple supers system. The rules are 30 pages long. It is available as a pdf ($5) or as a dead-tree product (10 bucks) as well, both through rpgnow.com.
The gist of the system is that you have 3 stats, rated 1-5. Brawn, Agility, and Mind. For an example of scaling, a 1 Brawn would be a typical person, a 2 would be peak-human, ala Batman/Captain America, a 3 would be some super strength, like Spiderman, a 4 would be a typical brick, able to lift a dozen tons or more like the Thing, and a 5 would be practically limitless strength, like the Hulk, Thor, or Superman. A typical "street level" character has 7 points to spread among these stats.
In addition to stats, you have powers. Typically 9 points worth, and they also rank at 1-5 points each.
Thus, you avoid some of the complexities of other systems that may require a calculator to build your character. You are dealing with 7 or 9 points-- not 250 like in some systems, where you must apply fractions to figure point costs of individual powers.
Play is as simple as character creation. Everything uses 2d6, multiplied by the stat or power being used. If you roll doubles, your dice "explode", allowing you to roll another die and add it before multiplying.
It is a very fast paced game. You can run an entire adventure in 4 hours. In some hero systems, 4 hours would be one combat.
Here is a link to it that will support ENworld:
http://enworld.rpgnow.com/product_info.php?cPath=1_18&products_id=4657&
Also, it encourages ways of winning without having to knock stuff down to 0 hit points. If you are fighting an enemy like Sabertooth, for example, who keeps regenerating all the damage as fast as you can dish it, perhaps the way to win isn't by doing damage! Finding ways to immobilize or stymie villains are just as viable, and as we see in comics, often used in preference to "I hit it till it stops moving". The x-men don't always blow up sentinels (wolverine may not be there). Beast might jump on its back and hack into its computer system, for example-- something that could not happen in many other RPGs.
Fun things I have ran with this system include: Teen Titans and X-Men. When I ran the x-men game at a con, one of the players really wanted to be Kitty Pryde, even though I did not have a pre-gen for her. He made her in 20 minutes with the book and a piece of paper & no help from me. [I liked the build so much I made her a pregen for the next time I run it].
There is a sourcebook available as well, called Megapolis: A City of Supers, which has plenty of super heroes, villains, neighborhoods, a magical realm, and story-arcs that take place throughout an entire year.