Manfrotto 718B

Holds my Nikon D80 with lens perfectly

Great, Thanks

It was me with the round legs, they are much more stable (cylinder, square / surface area all that jazz about arches and stable shapes, all the things I slept thru in school.)
If you can afford to be choosey, there are three brands you should stick too (MHO here)
Gitzo, Bogen or Tiltall, walk in any studio across the country and guarantee you will find one of those three in the corner, or in a location kit. (not counting the big studio jobs and large format tripods, those three may be pricey, but they will last you the rest of your life, any one of those brands. I own a Bogen and a Tiltall, could never afford the Gitzo, lol.)