Im running a poweracoutstik ovn1-4000d amp to them off a batcap 800. Which subs are going to have the best spl/sq rating?

havocs are SQ woofers with high power handling capablities, the orion is more SPL oriented with no where near the SQ as the havocs, and the RE MX is kinda different than both, but closer to the Orion, where it is meant to play music loudly, but not same SQ as a true SQ woofer. If you are looking for a single woofer setup, why not the Mayhem? for a two woofer setup, I say havocs FTW. of course remember, that amp will probably push ~ 65% of the power it says after voltage loss.

All of the drivers you listed can sound good an get loud, as so much of it is based on the install. But which is the smart choice and best company to go with? Well you are already in the Ascendant section for a reason.