Well, you just pre-empted the two biggest I could think of off the top of my head...
*****
Conceptual Speed- Blitzing: while "Comic Physics" must always be taken with a grain (or bag) of salt, it does take some *proper* interpretting to discern *specifically* how *different* qualities of speed, reflex, time-perception, and agility interact with others, whether faster or slower (that is, Barry/Wally isn't always going to have the "temporal" edge, in terms of reaction time or effect, and while - as you cited - Peter's SS/agility/reflexes are very impressive, it not going to necessarily do squat against a *proper* ultra-fast or area attack).
Yeah, I know -- plenty of people ignore superspeed, conceptually, in forum fights (and while not trying to offend anyone, it does seem that some hardcore Marvel fans seem more guilty of that than others), but just as many translate it as "insta-win", both in a forum and in the comics, and that isn't always the case as much as it appears on the surface...
EDIT: damn -- my slow typing got multi-pre-empted... *sigh*
Oh, and as stated by others above: definitely "Hulk Smash"...
In all honesty strengths and weaknesses are played up and down based on who likes or dislikes, or who is arguing for and against a character. It's what happens in debates. Nothing really new there. Most don't think Spider-Man is untouchable, just like most don't think Wolverine can't be hurt. Those are only a small segment of a large community.
The most difficult forum powers would be: speed, magic, and reality warping. These are pretty much autowins unless someone is even more "infinite". This tends to happen in threads where characters go beyond high herald, where it is really about who is more "infinite".
Good thread though.