I like to do this kind of thing. Humor me if you will.
If they happen today, who wins the rematch?
BJ Penn vs Diego Sanchez- let's make this a 162 lbs catchweight fight
Benson Henderson vs Anthony Pettis
Dan Henderson vs Anderson Silva- let's make this a 195lbs catchweight
Andrei Arlovski vs Roy Nelson
Carlos Condit vs Rory MacDonald
Dan Henderson vs Rampage Jackson
I don't think Sanchez has anything for Penn (I'm talking about the BJ Penn that lost to Edgar, not the BJ Penn that is retired and probably out of fighting shape).
Personally I believe Benson hasn't gotten much better since his WEC days. He's just always been that good and he's been winning some decisions that he should have lost in my opinion. Pettis has improved a lot though, I think he'd finish Benson this time around.
I'd pick Anderson over any opponent at this point so this is a no brainer.
Nelson could have beaten Arlovski the first time around but one of the worst standups in MMA history sealed the deal for Arlovski. Nelson via knockout.
Condit via TKO again.
Current Hendo would beat the Rampage that lost to Bader and Glover.