well for game server you don't really need a control panel, just a way to remote in. If Linux, then easy (SSH) if windows, then you may want to consider a VM on a linux server, then use 2 VMnets, one with the NAT so you can forward ports internally and SSH tunnel through, then other interface for the game server port. This way you don't open up VNC/RDP to public.
For webhosting I could not help as I'm too cheap to buy a control pannel so I'll be coding my own. cpanel is pretty much the standard though so if you're going to pay for one then thats a good one to look at.
Interworx is great, though not really all that new. We've been using it for several years now. It is very well put together, much more efficiently and unobtrusive than the other options, and very simple to use. I highly recommend it.
If you're running game servers, not using a control panel at all will give you the best performance. Otherwise, with WIndows, TCAdmin is highly recommended.
I can run the gameservers on my own. I don't really need a control panel for that. I was talking about what web hosting control panel would use the least amount of resources to affect the gameservers the least amount in performance.
I heard Lighttpd is much more efficient than apache and sometimes more secure too. Are their any major control panels that work with it? I wouldn't be comfortable enough to do it all through linux. However I've used Cpanel, Hsphere, and some others and they are pretty easy, however they have all been with apache. I would use litespeed, but they are super expensive for one server. Lighttpd is free!
Honestly I'm not sure yet. I am trying to plan out the software aspect first. I am trying to build the server based purely on performance. I want the Control Panel that uses the least resources and the fastest http server too.
I am still debating whether to rent a dedi or two, or to buy them outright from someone and then colo it.
If you want pure performance then skip a control panel altogether, if you know what you're doing. Otherwise, you should be able to put Litespeed over the top of basically any Apache based control panel configuration without much issue.