Help, opinions, and expertise needed!

Alright so right now i own two 10" type r's (not the newest but not the oldest. they handle 500w each) these are in a decent bandpass box at the moment. I am constantly buying and turning over subs for money so i would like help deciding if i should keep the type r's.... or sell them and buy something else. i am looking for a pretty high spl sub with hopefully a decent amount of quality to it. So, if it were you what sub would you buy while staying pretty reasonable. I like alpine and JL and am familiar with them, but i know there is much more outside that little box. So in summary what could i get that is better than my alpines for just as much money or less. any brand....but something i could find used is always nice.

Thanks!