2 - Triple H
If he wasn't in his 70s, I would've put Vince McMahon in this spot instead of Triple H, although they'd both be pretty great feuds if Punk did come back to the company. But, the good news is, WWE could use Vince McMahon in a feud between CM Punk and Triple H if the former WWE Champion ever does return.
Punk and Triple H have worked together in the past, and even though WWE clearly made the wrong call by having "The Game" pick up the victory over their hottest star at the time, the overall feud was pretty good simply because it featured a lot of "real" moments.
Now that the heat between the two is pretty well-documented, a feud between them must happen if Punk comes back, as it would definitely bring out a lot more "real" moments, and it'd probably be a good match in the ring.