I think Robbie Shakespeare would argue that you don't need 15"s since he's most recently been seen using three SVT heads and 810 cabs. It's all a matter of preference. I think a 212 would get you where you want to go, but I think a 115 would as well. 210's are generally a lot brighter than what you're looking for, so I think it would be wasted in a reggae rig. But a 410, 610, or 810 would be pretty sweet because they have big boxes and can get deep tones plus quick response. But for a small one cab solution, I'd get the 212 or 115.