I don't want to seem like a smartass but I have to say that there's at least 3 hosts recommended in this thread that have had significant (ie, multiple hour) outages. I'm not saying that to diss them, which is why I am not mentioning their names, more to point out that even a host with excellent average uptime is probably more likely to have a rare extended outage rather than a bunch of little 30 second blips over the months... both of those scenarios average out to the same, but the former has a much greater impact on clients.
BTW, posting the uptime value of a server really only demonstrates that they've never lost power or crashed. A network outage could still result in the box unreachable for hours.
