I mostly prefer the yellow foams. I have used Chemical Guy's red "ufo" or whatever they call it. Felt neat in the hand, more dense than the yellow from Megs. Would I spend extra money for it? No.
I've also used some Viking (?) blue MF type pads. They're okay. They have their use, and so far I find them best for liquid wax (like PBs Natty).
I also tried out the polishing pal from Griot's, using one of their 3" black foam pads to apply wax. I liked this set-up very much. I was able to hand apply the wax much faster with confidence (I've dropped a few yellow ones in the past). I'll still use it from time to time, but I find that I like to move slower and by hand using the yellow foam. So it could be one of those "what's best for you, at that time" type deals.