in my wife's car, i have a CT Sounds CT-2000.1D Compact Class D for that same sub in a 1.25cuft sealed box. matches up nicely with very old re audio 800.4 running focal ps165 fx all the way around. everything sounds musical and does about 1300-1600w on music before clipping.
if you were to do an a/b listen with everything the same but just different amps. say ct sound 2000.1 vs zapco 6.0/arc audio xxk2500, you'll notice that the hit is not as fast/pronounced, but you would have to be really listening for it or have the ear for it and it has to be side by side.
i'de say, you would be happy picking any of the choices here, unless you got a picky ear. then it's just a rabbit hole.