Help Picking An Amp

I just picked up a alpine type r sub and I have been looking for a good amp. So far this is what I have found:
Alpine
http://www.sonicelectronix.com/item_6470_Alpine+MRP-M450.html
Infinity
http://rover.ebay.com/rover/1/711-1...150212229935&Category=64570&_trksid=p3907.m29
Kenwood eXcelon
http://rover.ebay.com/rover/1/711-1...ryZ64570QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

The kenwood is a really good deal because that amp is usually a lot more and the eXcelon amps are supposed to be really high quality amps but I found a few reviews and I am getting mixed opinions. A few people said that with the gain 3/4 up the amp shuts off and that they had issues with it shutting off when the volume was up high but they could have been running it at 1 ohm (they never specified) and I am going to be running mine at 2 which might be more stable.

The alpine would under power the sub a little which I want to avoid and the infinity might deliver too much but then again some of the reviews I have read say that it delivers less power than stated.

Let me know what you guys think about these amps.

Oh I didn't even realize that I never mentioned the size it is a 12 and it is 500W RMS dual 4 ohm voice coils so I can run it at 2 ohms.

I bought the kenwood excellon for $145 after shipping since the amps is normally over $200. The alpine amp would have been about $30 more and it isn't 1 ohm stable so I figured this was a good deal if I want to upgrade the sub later on or add one.

I only have one sub so I can only get 2ohms but the amp I bought is 1 ohm stable if I decide to add one and it is 600W at 2ohms and 600W+ at 1 ohm. Thats a nice amp I actually looked at that one but the kenwood eXcellon was such a good deal I had to get it. The eXcellons are supposed to be really high quality.