If the options are Q10 and Z1, the choice shouldn't be that difficult, it is Z1 hands down. Contest between Q20 and Z1 would be much closer.
Z1, in my opinion is the smoothest ball head with sweetest of sweet spots out there at the moment. Q20 is a close second with slightly more rugged build than the Z1. If I were you I would only look at Q20 or Z1.
Edited to add.. Your RRS L plate with fit on to any Arca Swiss style clamp. I have fitted my Z1 with a wimberly C-12 clamp because I wanted to use it with a wimberly sidekick