i agree, it depends on the size of the top water and terrain. Typically, i use over 7' MH - H. My weapons of choice:

Megabass Destroyer:

F7-71X7 Aaron Martens  

Evoluzion Super Diablo C40

Evoluzion White Python C40

 

I use 6' M/F or 6'6" M/F St. Croix Premier most of the time.  Depending on lure weight I might reach for a MH if needed. I just don't fish topwater baits very much.   I have a pair of the Avid 6'2" M/XF that JFrancho mentioned but use them strictly for jerkbaits, never considered them for anything else but I suppose they'd do real well with Pop R or other smaller lightweight topwaters.

I like to use a fast action rod, I've got a Savvy 703c, I could do with a bit of a lighter rod, but I already spend too much on fishing. I know that some people like the mod-fast actions, I tried it and I don't really like it that much. It's just not as crisp of a walking action.