If I may (hoping this is not too off-topic), I'd like to comment on what I always thought was the best defensive ability.
Say we have, for showcasing each ability...
Juggernaut: invulnerability
Wolverine: healing factor
Spiderman: reflex speed
We start off with small caliber fire.
Juggs takes it on the chest: no problemo.
Wolverine takes it in the chest: after a sec or so, no problemo.
Spiderman dodges: no problemo.
We build up to, say, RPGs.
Juggs takes it on the chest: no problemo.
Wolverine...well, it may take a few seconds or minute, but eventually he's back on his feet, good as new.
Spiderman: no problemo
So far, invulnerability and reflex speed seem to be faring best.
We keep on increasing the power of the weapons until, at some point, we will probably first exceed Wolverine's capacity to recover, at least within a reasonable time frame (ie, before the Bad Guy can strike again, taking advantage of the time it takes for W to recover).
We keep increasing the power of the weapons, until, conceivably at some point, Juggs starts to feel it, or at least get knocked off his feet or in some way becomes temporarily incapacitated.
With Spiderman (or Batman, Daredevil, Cap America--take your pic), it doesn't matter how powerful the bullet or bolt is because they're just not making contact with their target.
Perhaps I did not pick the best examples to showcase each defensive power, but I think I was able to highlight (if not prove) my point, at least with non-mass-destruction attacks. But even these could be offset if the simple ability to Get Out Of The Way was combined with sufficient warning sense.