My main host (other then dedi's and yank bandwidth monsters) is Evo Hosting
http://clients.evohosting.co.uk/aff.php?aff=060 (Aff Link) never had any issues with them.
Support is rapid, Tim the owner and Toby the tech are always reachable is normal support can't sort it out for you, one of them is usually on MSN for quick Questions.
In the last 3 yrs or 4 years, there have only really been 3 downtimes, 1 was hard drive failure, and 2 was server replacements, there have been the odd few minutes of downtime when the server has needed a reboot due to recompiles and stuff like that, but its rare.
They are not as such the cheapest but I believe its worth paying an extra few quid for quality.
Servers are hosted in the UK and MINIMUM spec is Dual Quad Core (8 Cores), 8gb Ram, and Raid 5 Hard Drive Arrays, so the machines are beefy.
The above is the only banner I got but shows you can idea of a high end package, which is on a special offer now with Unlimited Bandwidth.
Enter the discount code Gimme10 for an Extra 10% off too.
Also if you contact tim and the gang explain your unhappy with your current host, he's also willing to give upto 6 months free on transfers so you don't lose money with your existing hosting, and Evo will even transfer your files, databases, etc if using Cpanel so you don't have.
Take a look around the site
