It really is amazing how stable a good tripod is, and if the head locks up solid, shooting is a piece of cake.As others have mentioned, the RRS is the gold standard. I didn't want to spend that much so I bought one from two vets. It is amazing.
Before I had the Sirui that is well liked here. It is good but the stability is no where near as good as the better tripods. I shot out to 800 yesterday standing and it was easy.
Don't forget the head is important too.