I use the cheapest Actron (the small one) and keep it in the car with me. In the winter, I was throwing CEL's a lot (I'm thinking due to coil packs getting wet and causing a misfire) so I would just pull the code and reset it.
The more expensive one (which my friend has) can pull the fuel trims and stuff which is awfully handy, but I couldn't see spending that much for the next bigger model
I'm happy with the small one!