For the future, don't bump the threads that old, but I'll at least give mine:
1. Bob Barker (even with the fact he had his clear misognystic moments, the dude was the epitome of game show host.)
2. Alex Trebek (one of the smartest game show hosts ever, one of the most popular and one of the most respected in multiple areas.)
3. John Charles Daly (This one might get me some flack, but JCD was a fantastic game show host. He was personable to everyone from contestants to celebrities. He hosted What's My Line to absolute perfection. Of the non Bill Cullen hosts, he'd be my pick for best host of the 1950s. (I'm not a big Bud Collyer fan.))
4. Bill Cullen (I just name dropped him, but the man was the most flexible game show host in American history. He always took a job with absolute dedication, no matter the format or the concept. If there's a definition of Mr. Game Show Host, it was him.)
I'd have to think for 5-8.