I think you've mostly answered it yourself. Diva is probably a workflow experience closer to something like the synths used in classic electronic. As its a classic analog subtractive workflow youll probably learn those fundamentals as well. Pigments is newer, has a more novel workflow and more synthesis methods (wavetable, granular etc).
Full disclosure : have not used either. Have watched reviews in the past. If you've used both yourself, you're more qualified than me.
Eventually you’ll have both of course :) VST GAS is a thing too . Thats the long term implication.