You ought to balance size (e.g. host europe is very big, and thus has greater resources) with flexibility and responsiveness (host europe I guess probably operates a call centre). Do you mind that, or would you prefer a smaller company with a more personal approach, bearing in mind the bloke giving support may also be the one who was up @ 3am rebooting the broken file server.
Finally, do you want your hosting company to be anonymous? FastHosts etc. may have a completely brandable control panel so your customer never needs to know who you're using to host your stuff with. Others may prefer you to promote their brand to your customers, acting as your "hosting partner" - in recognition that we can't be all things to all men, and it is good to team up with some one who is good at hosting.