velodyne dd plus? still considered best of the best?

+1 on paradigm defiance.  Absolutely tremendous subs for music and movies.  I sold my E112 stacked pair (poor mans / smart mans F212 pair) and I am running just a pair of X12 Defiance subs and they are unreal.  Just as tight as the JL, around the same output, yet they’re made in Canada and have the best room correction around (way better than the F113 v2 I had).  
The only caveat is that they are boring square boxes.  Although the woofer does look very cool.

See if you can find a local dealer that will let you take them home.  They will shock you.

I almost went with a pair of the Rythmik 12" subs.  But decided to go with the REL S3's because of their high level connection.  They blend quite well because when connected that way they act like an additional woofer to help extend the bass without it sounding too boomy.  However, I really like the direct servo technology uses in their Rythmik subwoofers.  However, since they are sold direct it was difficult to buy them without hearing them first.  I have heard they are very musical.

So, did you ever decide on a sub?

The DD and DD+ can be an incredible value in the used market considering their performance and features. Servo motor with manual control, auto as well as manual room correction, visualizing frequency response, low distortion, very well built, massive amp, sealed, remote, etc.
The DDs probably have the smallest cabinets in their respective woofer sizes of any premium sub. The DD+ versions have bigger cabinets but lovely aesthetics with the curved sides and esp the black glossy veneer. 

The DD subs use to be cutting edge, but like others I would not purchase one now with the new ownership and questionable support.

One of the most musical subs I've heard is the Aerial Acoustics SW-12, however these are pricier than the others you mentioned.

I would go with the SVS sealed and not look back.

Good luck.