Agreed stab motor are the best but cost almost double if I remember correctly. I've used a Darkmotor for a while and never had any problems.
Stay well clear of the cheap motors. They dont last long and I've had loads of problems with them in the past.
I have a Darkmotor fitted to a 1m dish, works well, had it about 3 years now, no problems really, occasionally when I drive it to a satellite it shows no signal, I have to move it to another satellite and then back again? Apart from that it's fine.