"Changing Keys '83" has got to be the best. That's like game show theme perfection. '89 and '92 are pretty darn good as well, but I think the amazing ending to '83 pushes that one over the top for me.
"Tic Tac Dough '78" is made of pure awesomeness. I have no idea what that weird instrument is that's playing in the song, but I love it!
"Family Feud '76." Or "Family Feud '88." Honestly, it makes little difference to me, and I really don't have any preference there. Something really cool there is that, for years, what I thought was the "ending" to the theme was actually not the ending--that there was actually a good bit more to that theme that came after what I thought was the ending!
"Press Your Luck" is... well, I'm not sure there's anything specifically outstanding about it, but it's about as "classic sounding" game show theme as you can get! Same with "The $25,000/$100,000 Pyramid," also right up there.
And to bug sidey--and because it was a great theme--"Scrabble '84," which is... just really good! Actually, the '93 theme was good as well, but it can't really compare to the '84 one.
And "The Price is Right." I'm not sure it's really the "best" theme, but after being so comfortable hearing it all my life on the best game show... hard to not appreciate that one.
Least favorite... I dunno'. "Tic Tac Dough '90" is certainly up there, though. I'm tempted to go with The latest few "Wheel of Fortune" themes, though, which have just sounded like a bunch of random noises.