If you're willing to spend the $500 then you should probably go with a Radion XR15. I don't think anyone is ever unhappy about buying those. It'll be overkill on the 12 gallon but should be very nice on the 40 cube.
Personally, I've got a 40 gallon AIO with an Ocean Revive over it. I like the idea of the spread out LEDs in it, but to be fair it really hasn't had to prove much yet. FWIW, it's helping keep some nearly dead SPS alive, my purple stylo looks great, and my GSP and zoas are growing, but that could just be the stability of the tank.
I've got a Viparspectra on my tank at home and I'm liking the results so far. I modified it to be ramp-able with my Apex. So it's nice, but if you're willing to spend the money just going all out from the get go and getting the Radion is probably the way to go and if you've got a decent LFS they should stock them.