Hey man, Honestly the 10" will be perfect if you're short on space. The SQ will be great, and plus you'll get a lil bit of pounding going on. But if space is not an issue, Please get the 12's! I swear to you, if you've ever heard the L7 12's, you wouldn't even notice the difference! The SQ and SPL factors apply to this sub. I mean, the SQ is still not on W7 levels, but, I wouldn't be surprised if SQ-heads start to rank this sub as a new prospect! As far as the SPL, man oh man, I can't put it into words. Thursday, I sold my 15" Squares with the custom box, and got 2 15" CVXs in single vented box. For my 2nd system, I don't think it gets much better! I'm a big Kicker fan, especially for their squares, and I've been kinda disappointed in their performance lately, but with the Solo X and this CVX, they are really getting my attention back!
The 10's or 12's would be great. Put them in a ported box tuned at 32 hz and you'll have a great sounding system. Go with the 12's if you have the room