Ooh Ooh, I got a few.
CM Punk - I still think he'd be green, just an evil green. Think Sinestro right before his heel turn.
AJ Styles - White. He's one that could fit with several of the colors, which makes him a prime candidate for White in my book.
Sting - Like Styles, he would fit with multiple colors. Will? Check. Compassion? Check. Hope? Check. Displayed all those traits during the NWO war. In fact he could do one better than AJ in that he could probably pick up a Yellow ring to boot. So Sting gets the white ring.
Chris Jericho - Green as a face, Orange as a heel.
Jumpin' Jeff Farmer - Blue. Yip!
Tommy Dreamer - If there ever was a candidate for Green, it would be him. Just keeps getting up. Though his jobber status may regulate him to Blue.
Nick Bockwinkel - Yellow. Intimidation, craftiness, always plotting. He'd use fear tactics with the best of them.