Keep an open mind and try to test as many poly synths as you can without getting too hung up on a feature here or there. I used to have a Peak and it had everything and the kitchen sink in it. yet I barely did any sound design with it because I didn’t find it very intuitive. Especially the modulation, gave me flashbacks of trying to sound design on my D-50 with all that menu diving. On paper it was everything I wanted, but I was looking at features, without any insight on how it would be used as an instrument.
Both the Take 5 and Prologue seem like well-laid out instruments that are intuitive sound design tools / instruments. The Deepmind has a lot of menu diving and a pretty awful keybed if you go the keyboard route. Does that matter to you? I didn’t used to think it mattered to me, but after the Peak and more recently buying and being very disappointed with the OpSix, I’m starting to come around to the idea that interface and intuitive design is more important than specs and even gasp sound.
I recently traded one of my D-50s (yeah I’m kinda obsessed with this synth and have a couple) for a Roland System 8 and now the System 8 is possibly my favorite piece of gear I’ve ever owned. Yes, it’s ugly. Yes, it’s plastic. Yes, it’s digital. But IMO it sounds lovely and is so intuitive and well-laid-out that sound design on it is fun and quick. Great patches just flow out of the thing. I would have never even considered that synth when looking for a poly, but there you go… sometimes what is “best” for you isn’t necessarily the best overall synth.
TLDR Just try all the synths any chance you get and make a decision based on what is the most intuitive creative tool for you.