I prefer a sawback machete (top of blade is a saw blade). Why not? If you need a saw, it'll do that too. The more versatile, the better.
The Ontario sawback blade is good, and locally at least there is a shop that has a sheath for it that sharpens it each time it is drawn. Pretty slick.
Also check out the Gerber Gator sawback machete. I just picked up one of these today - looks to be very well put-together, nice feel. Only got it because the shop with the Ontarios wasn't open when they were supposed to be, but I don't consider the Gator to be inferior. Only difference to me was that I had kinda wanted that cool sharpening sheath.
By all means avoid those Wal-Mart bendy pieces of crap. Been there, done that.