My all time favorite Shawn Michaels match is his match against Chris Jericho from Wrestlemania 19. However, plenty of people have already described that match to perfection in the Chris Jericho thread, so there's really nothing I can add to it that hasn't already been said.
So, I'll go with two other HBK matches to talk about:
Shawn Michaels vs. Jeff Jarrett - In Your House II
AMAZING match. In my opinion, in ranks right up there in the top three Intercontinental Championship matches of all time. And if you look at the matches to take place with that belt on the line, that's some statement. But I stick by it. The match was incredible. It was just a face pace match that seemed like only five minutes long, but in actuality it was over 20 minutes. Not many matches pull that off.
Shawn Michaels vs. Vader - Summerslam 1996
This match was fucking terrific. I loved it every second of it. It was unpredictable, all over the place, and just Shawn Michaels being Shawn Michaels. You know that saying "Manny being Manny"? Well, in 1995 through his last match at Wrestlemania 14, that statement would've fit PERFECT for HBK. He was such an unprofessional prick, but god damn was he entertaining. And this match is a perfect example of that. 30 minutes of non-stop action, with Shawn completely being an asshole and abusing his backstage power, daring Vader to cross the line, while also putting on, along with Vader, a fantastic performance. Gotta love it.