I have the PC, and although i've not been able to compare to the others...there are several things I don't like about it, depsite the fact that it REALLY gets the job done: call these minor complaints in ergonomics.
1. It's LOUD. I have to wear earplugs when I detail my car.
2. It's heavy: arm gets tired when running one-handed.
3. The side-mounted stabilizer bar is removable, but totally useless. (d-bar looks much better!)
4. Gets HOT!
5. Plate backer removal is cumbersome and not intuitive.
6. Old-style velcro pads (on my model) tend to rip foam.
Again - not sure how these stack-up to other models, but these are my most obvious complaints with the PC.
If you can ask a Meguiar's rep how their prod. stacks-up to these issues, I think you'd be ahead of the game.
good luck.
No matter what you choose -- you'll have a mUCH better machine than a cheap Ryobi.
gr