I've been with many hosts over the course of 8 years. I just started using Webfaction a few months ago.
- 60 day money back guarantee. Try it and see if you like it, risk free.
- Great support. Both tickets I've filed were responded to within hours. The answers were helpful and friendly.
- Full SSH access at no extra cost. SFTP as well.
- Mailing lists and unlimited email accounts.
- Full DNS control.
- MySQL/PostgreSQL support.
- Django, RoR, etc all run without a problem. 1-click installers for these sorts of things.
- Subversion repos and such over SSL.
- Ability to compile/install additional software that isn't in the 1-click bin. I've installed development Django, git, and a couple command line tools in my $HOME without any trouble.
- I find their default web-mail client horrible (RoundCube). I decided to use Gmail instead.
- Slightly less inexpensive when only ordering a year at a time compared to other hosts.
- No domain name registration. However, I find this to be more of an advantage for someone more experienced. More control and flexibility.