IF your going to be doing a wet sand/polish get the 6" sander/polisher. I have performed many cut/buffs with mine, very similar to that one pictured.
If you can, get yourself a dual speed or variable speed, it is nice to have a selection of speeds when compounding and/or polishing.
With the 6" one, it is nice because you can put a cutting wheel on it too and cut stuff up, very handy.
I have never used the 10" style for anything, dont even have one.
If you are new to buffing and polishing, make yourself a test sample first and practice, it is nicer to not worry about "F"ing somting up that
you have alot of work into. "BEEN THERE,DONE THAT"