AoCh was perfect before the sprint nerf, it was very fast paced if you played a footman sword.
Now I've been playing HL:2 Deathmatch, because of the random fragging aspects of it. You have to watch your back all the time, and there are a good number of weapons with different timing and ways to use them.
Being able to avoid damage and strafe/trick enemies will be crucial in DF, so I think any game where you have to use aiming, timing and dodging at a fast pace is good.
Weapon switching will be big too so it's a good idea to get used to using all of your mouse buttons to your advantage.
I've got a little bit of info that can help anyone with FPS. I'm just not going to post it here on the public forums for all the phags and phanbois to use.
