Which subwoofers to buy? cant figure it out?

I have found a few different set ups and would like to know which one will give me the best b and will last. I have one JBL gt5-15" sub 300w rms. or one Cobalt CO154 15" 250 rms. or one 12" Re x12d4 175w rms. or two 12" Hifonic HFi12D4 @ 300 rms for both. Im looking for the best lows and kick and durability.Thanks very much suggestions helpful and appreciated