Best Minecraft server hosting service?

http://voodooservers.com/ is pretty good

For affordability and quality, you might want to consider renting a low end virtual server (with guaranteed resources) and handling things yourself. You'll be paying more, but you wont be fighting 50 other server instances for resources due to unscrupulous hosts overselling ;) An alternative might be cloud hosting, though in my experience a fixed virtual server instance is often cheaper at the low end of things (when you know you're gonna use that 2gb of ram) - services like EC2 win out with scalability.

As to name companies, I've a few virtual servers of various sizes with NFO. There are certainly cheaper companies out there, and it's wise to shop around, but in my opinion it's worth paying a few extra dollars a month for reliability (99.9% uptime this year, most outages due to kernel updates and such).

Fragnet.net is what I use. I've never had any issues with them that weren't my own doing. I'm on their $20 server since I'm using FTB Monster modpack and need the extra ram. Never have any issues with memory or anything unless we're going crazy with Mystcraft.

I think that this is the best, nice service (no-lag, possibility to configure the ports, and create a website) and awesome support http://www.verygames.co.uk/product/21/Minecraft_Server/location_louer_Minecraft_VQS_infinite