I've been with
http://www.LiquidWeb.com for years. Not the cheapest out there but my uptime consistently runs 100% month after month. I make a lot of money while I'm sleeping so uptime is my #1 priority so I don't mind the little extra I pay to be with them.
24/7 Email/Phone Support
100% Uptime SLA
Owned Data Centers
They have done quite a few extra security tweaks for me as well. Hear a few other names usually mentioned by others as being decent ServInt, KnownHost etc... but I've never personally used them so can't personally vouch for them.