We're now switching over to JL W0s for a woofer in the $100 class. But, we used the Polk dBs for years. Its a low mass and fairly efficient sub that works well with low to moderate power and models very well in a small sealed box. Ignore the factory recommendations of .88 cu. ft. Instead use a 1.0 minimum to 1.2 maximum gross internal volume for a 12.
The Polk MOMO sounds great in the right ported box but is an absolute dog (not just a woofer) in a sealed box. In any case, the correct box will have a big impact on the performance you get. Negative reviews can be misleading because you never know if the user executed the box, tuning or installation correctly. Stay way from off-the-shelf car stereo boxes. The seams will fail in a single season, even though the carpet conceals it, and the woofer will soon fatigue and fail as a result.