Some operating systems I'm looking at are:
- OpenBSD 4.8
- FreeBSD 8.2
- CentOS 5.6
- Ubuntu Server 10.04 LTS or 11.04
As for sticking with Linux, Ubuntu Server is definitely a tried and true operating system, but I'll need to see what the major differences are between 10.04 and 11.04 because I really like the idea of running a LTS version which I'm on now.
I'll post some updates as I run my testing.