Brand selection is one-part technical specs, three-parts personal pr
Simpe rule of amps: The goal is to find one that comes close to, but not exceeds, the RMS rating of the speaker(s).
Modifier Rule One: Every speaker has a range, RMS is an ideal value for continuous operation. The speaker's tech support can help you determine how much tolerance you have to go above and below that magic number.
Modifier Rule Two: Most speakers operate at PEAK efficiency at between 75%-85% of RMS rated power, not 100%
With those rules in mind, I personally, if told to meet your situation, would look for a brand I liked at around 600W RMS. I would also call Eclipse and verify that 600 is okay for the 8122. I'll bet cash it is.
Depending on how rough you use them, though, I might change amps when I changed the sub. Hard-thrashed amps wear out just like hard-thrashed subs. It all comes down to useage.
Hope that helps. It's my personal opinion, and I'm sure there are many different ones out there.