I think the problem you are going to have is finding someone that ticks "all" the box's - not many UK hosts that I know are a member of websitespark for example...
Is websitespark a very important factor in choosing a hosting company for you? I take it that you would need Windows Server? (which rules me out as I only deal with Linux servers)
As Monaghan says... Large companies can be very hard to deal with at times, yes they have the infrastructure and a large number of employees but the vast majority of those employees are just that - they clock on and clock off... They won't care that your website is down once it's time to clock off!
Smaller companies are usually better to deal with but have an increased risk of going under (but I don't think any size business is more or less at risk at the moment!)
There is another solution of course, it's not the cheapest and doesnt include websitespark but it combines the best of both worlds.... PM me for more info
