There are wast amounts of different autosurfs out there. Or rather not so different. Some look exactly the same except for the name. It can take some time before You find the one's that work best for You.
These are the ones we currently use.
What we are looking for when we try out a new autosurf is reliability. If it's down all the time it's no good. The second thing is if there are sites with framebreakers, pop ups that messes with the timer and hijacking scripts.
If You are getting kicked out every 5 minutes becouse of framebreakers or if your surf window is highjacked it's better to move on to another autosurf. If the admin can't keep it clean it's probably going down anyway.
We also prefer autosurfs that allow site rotators. It's pretty nifty to be able to use one URL for all your sites.