I've got several VPS's from a company called FutureHosting.biz and they have been really running smoothly -- even with cpanel/whm/fant/rvskin. I actually was searching in WHT myself a few months ago, and that's how I came across them. I've also heard of KnownHost, they seem to lack guaranteed RAM in their packages, but apparently their sales staff mentioned most users can get up to the Bustable RAM. Hopefully one of those two will suit your needs, apart from the ones webfreak08 already mentioned

Good luck!