I too am an electronics beginner - however, making projects like the UHU servo driver are great learning experiences.
If I understand everything correctly, the UHU servo drive will handle more power than the Geckos, which for me was important. I believe the UHU servo drive is also on par with the Rutex drives for power.
Cost is going to be within $50.00 between any of the three (I believe).
For "plug and play", the Gecko, from what I hear, is the easiest to setup. I believe the Rutex might be a bit more difficult to setup up, but have heard it isn't too bad.
I don't know how difficult setup for the UHU drive is as I have not gotten that far yet -hopefully in a week or so for bench testing of the servo.
For me, I would probably pay the same for the UHU servo drive as either the Gecko or Rutex just for the learning experience. Sure, it's a lot more work, and at times frustrating trying to figure out "whats what", but so far I have learned a lot already - and it is tough to put a dollar value on that.