Which subwoofer should I get?

Hi - I have the following system:

Magico A5 speakers

Gryphon Diablo 300 integrated

Merging Nadac + Player + Power DAC

Purist Audio cabling

I love my system......but I had the opportunity to use an SVS PB-2000 pro (home theater subwoofer) for a few weeks, and it really improved the overall experience.

I have the opportunity to purchase a REL Carbon Special sub (used) or purchase an SVS SB 3000 Pro. I really like the fact that the SVS subs have so many user adjustable features, and can be adjusted on the fly from an app. I've been told over and over that the sonic qualities of the REL far outweigh the advantages of the SVS subs. Would love to hear from you regarding this issue.

So, in brief, should I go for the REL, the SVS, or some other sub (if so, why?)?

Thanks - Matt