I'm puzzled... I need the best uptime possible. There is obviously a big difference in price. If you were to host company web sites that can't stay without e-mail, which company would you contract?
If you need e-mail uptime, then use e-mail accounts from advanced e-mail providers. If you buy just 1 server, you are asking for trouble.
You can use webmail.us - they have over 100 servers at Rackspace- you will get some good uptime at about 12$/year/1GB e-mail box. Or you can use gmail for dommain, you will have a gmail e-mail, but with your domain, not gmail .
Your website can be hosted anywhere... but if you want e-mail uptime, then use dedicated e-mail services.
If you need 100% uptime, 1 server won't give you the uptime you need. You need a loadbalancing solution, or at least to be hosted on such a system. Unfortunality, TGL isn't ready yet for that, they are new.
If you don't need 100% uptime, then you can buy a managed server from a decent company, there are a few here. Look for old WHT members and see the reviews they get for their services.