Which do you prefere and why?
I had a bad experience with the roller. Torn calf muscles on both sides, with the doctor estimating a recovery time of 12 weeks. Also overworked shoulders, wrists and back from holding myself up a little too long.. I hadn't done much upper body weight training or conditioning beforehand. That's what put me off the roller.. for it to be safe I'd have to really increase my strength and stamina before even starting on it, then maintain it for as long as I wanted myofascial release.
The Stick on the other hand will be a part of my routine as long as I'm active. I've got a lot more control with it, helping me get an effective massage. If you have lean muscles, that's doubly important. With the Stick I start off with a few light strokes to warm up the area, then go progressively deeper into the muscles.. something I couldn't do with the roller, its pressure being the same from start to finish. I can get a good massage that way. There's also little or no pain with the Stick, and it's easy to relax the muscles.
I think the roller would be well suited for certain people, such as body builders and people who have naturally big muscle mass, but for the average cyclist, I'd recommend the Stick.