DDC 3.1 and 3.2 are both very good, but if you have the option for either, 3.2 and 3.2x ( I think there was a variant like this called a 3.25 or similar) corrected an old 'bump' start issue where the impeller sometimes would not start at power up due to it powering down a certain points between poles. The 'bump' start comes from having to tap the top of the pump and it would be just enough to start up.
Hopefully you're getting the 18v or higher pump models, which are the better performing versions as there are also 12v versions which have lower flow and head specs. There's also some DDC version which are actually 6v, and built on the same architecture, but for parts like AIOs and the like.