I have been on Powervps, great support. But my vps started to go too slow, tried fix it, but I got tired to fix.
Then I changed to jaguarpc. Fast server but the support confuses me a lot. Got a site offline for 5 days and they could not fix dns issues. (DNS issues is a problem that I had since the first install on the server)
Now I'm with servint:
www.servint.com/
. Support is slower than other 2 but they solve the problem quickly and they know where to look for. The vps performace is really good so far.