Go with FI.
I would get FI Car Audio.
Go with a FI BL.
FI SSD's are awesome too.
FI Q is the best sub ever as well.
FI BTL is the loudest and bestest sub on the planet.
If you have a budget and are looking for a sub, FI is obvously the best choice. No other information is needed, since they do have the best everything in every price range. No need to even gather any more information from you.
FI!!!
And before you ask, Ficaraudio.com