Love the Andis ACG Super 2 speed. We went through so many one speeds, they just never lasted long, within a year they were dead. I've had one of my two-speeds for three years and it's still doign a good job. Only thing is, the lever needs to be changed more often than on the one-speed!! ALWAYS change your lever when you think your clipper is crapping out on you, most of the time it will be brand new after this.
I've had Oster clippers, I hate them. They don't last long, the ones I've had have been awkward and hard to turn the button on. The last one was amazingly light, but died after three days of use, brand new. Never again.