1) Nick Ring - He's got his own sort of oddball pro-wrestling style persona. He's not the type of guy that has one hit power that will make Punk tentative for his first fight.
2) Kevin Casey - He'll be coming off suspension around the same time IIRC, and could be a very interesting matchup on the ground.
3) Andrew Craig - A really solid fighter to have to go up against first, but could really show what level Punk will be entering the UFC at.
Now for the 2 outside matches I am thinking of where CM Punk would probably be vastly outmatched, but would probably have more name push behind it.
4) Uriah Hall - Everyone that's an MMA fan knows about Hall's crazy KO on TuF, can he make a highlight reel out of a former WWE star?
5) Rich Franklin - Franklin has one fight left, and said if the right fight came along he'd be more than happy to fulfil it. Well, what about a fight for him that would have the biggest PPV buys of his career? That'd be a helluva way for him to walk off into the sunset.