I'll +1 EvoHosting.
They have a cage in BlueSquare Maidenhead and either Tim (Owner) or Toby (Sysadmin) live within 15 minutes or BS and they have an on-site office for direct maintenance.
Their machines are replaced shortly before warranty runs out, I think I am on my 3rd new server, which means its prob ever 2-3 years they are replaced. According to siteuptime.com the total downtime over the last year is around 1 hour.
They don't overcrowd their servers, they add a new server approx every few month to accom new users.
Support even for whacky extentions and such I want installed has been awesome, they are not nazi's with features either, if your nearing your limit and need 1-2 of something else adding, I'm pretty confident from my experience they would be happy to increase whatever limit, obviously if your request is silly they may suggest an upgrade instead.
Evo go all the way up to dedicated servers and like-for-like are around 40-50% cheaper than rackspace, and unlike rackspace they don't look at you cross eyed when you start talking dozens if not 100s TBs of bandwidth. Rackspace for 1 adult client looked at him like he was chasing the dragon and huffing glue when talking 10tb+ and after 30 minutes explaining they quoted silly money.