The Incumbent: Ricky Gervais, Extras
Who Should Win: Baldwin should win. Alec's alpha-male extraordinaire Jack Donaghy is brilliant and biting, and with the possible exception of Jack McBrayer, he's easily the most gifted comedic actor on 30 Rock, which is itself one of the funniest shows of all time. He was nominated last year and lost to Gervais for Extras, but hopefully the Academy will recognize the oversight this time around and set things right.
Who Will Win: Baldwin, for all of the reasons above. Shalhoub is in a close second, since his show is uncomplicated and has aired long enough that a statistically significant number of Emmy voters are likely to be familiar with it, but the unstoppable buzz of 30 Rock and the undeniable charms of Jack Donaughy (even Jennifer Aniston wants a piece of him!) should push Baldwin to victory.