I am also happy with the speed of tightvnc, although I have not tried others. I use it on my other Linux servers as well. Just a word of caution...although passwords are encrypted with tightvnc, the rest of the traffic being transmitted is not encrypted, which is especially important if you are accessing the pi over the internet. To fix that, you can SSH through a tunnel, which is what I do, or you can use one of the other vnc's that support transport layer security encryption.
My Raspberry Pi Project Page: