I think the specs on some of the brands you are considering are overstated.
For example, I have seen a JL Audio 250/1 kick the pants off of a Kenwood
mono block rated at 800 watts into 4 ohms.

You cannot rely solely on specs. A reputable dealer should be able to help
you. There are several decent brands available (not just JL Audio) and I am
sure you can find one that will work for you. You need to consider the way
you will have your subs installed (series vs parallel) and also the type &
size of enclosure you will be using. These will also have an impact on the
amp you may want to choose.

Regards,
Steve