The alpine and JL are nice, it's amazing how small the Alpine PDX series is, mine is mounted under the rear deck and powering the whole system. The JBL is ok, not that great, you're paying for the clear face for the most part with that one.
Make sure the speakers you pick match the impedance specs for the amp for best power. Also try stick with class D for sub amps if you can, they are more efficient and will put less of a strain on your electrical system, but overall it's not super important.
Here's a few more to look at.
These are 1 channel
http://www.woofersetc.com/p4424/D8002-- ... lifier.htm
http://www.woofersetc.com/p4224/LRX-140 ... lifier.htm These are fantastic amps, killer price on it.
http://www.woofersetc.com/p6558/D3-1000 ... lifier.htm
http://www.woofersetc.com/p4675/HCCAD12 ... lifier.htm Orion HCCA amps are no joke, not as mean as they used to be(they were "cheater" amps for sound competitions), but still mean.
These are 2 channel, but you don't care about stereo separation on subs, it's affects overall dB.
http://www.woofersetc.com/p6861/KS-3002 ... lifier.htm Great amp, you want to run it bridged at 4 ohm.
http://www.woofersetc.com/p4280/SRX-2S- ... lifier.htm another nice Audison
There's tons of great amps out there, I just picked the ones that stuck out to me on the woofersetc site. Pairing an amp with a pair of IDQs, I'd be torn which one to pick. For size and ease of install the alpine hands down, and I'm really impressed with how well my little alpine does. People are always shocked that I'm only running a single 12 and this little tiny amp powering it. The price on the Audison LRX is insane, and they are great italian amps. I love how ARCs sound, mmats are brute force with finesse, I have a long history with orion so I'm a bit partial, and the diamonds are pretty nice too. It's a tough one lol.
Never rely on "max power" or "peak power" ratings for speakers, amps, or anything else, that's a bunch of marketing BS. RMS(root mean squared) is all you care about. It's better to have too much than too little power for speakers, it's easy enough to turn the gain down, but bad for the speakers to not have enough power, you get into amp clipping which is hard on the driver and the amp.
Here's a neat page that you tell it how many woofers and what voice coil configuration and it will tell you what impedance they can be wired as http://www.the12volt.com/caraudio/woofe ... ations.asp If you are using 2 speakers and want a 4 ohm Load you want either 2 ohm single voice coil drivers, or 4 ohm dual voice coils (DVC). For 2 speakers with a 2 ohm load you either want 4 ohm single voice coils, or 2 ohm DVC. For a 1 ohm load, your only choice for 2 speakers is dual 4 ohm voice coils.