Hey!
I own all three. If I rank them by useage, it would be Minilogue XD, Digitone, Digitakt, because currently I am mostly sequencing with my Deluge. Minilogue and Digitone are more or less used the same.
If I would have to choose only one, I would choose the Digitakt over both others.
I can archive a lot of what the others do with the Digitakt, it just takes a lot more time sometimes. You can do so much with samples in it, and with tons of Single Cycle Waveforms and tons of sampled synths out there, I am sure, you can produce a full album on a Digitakt!
If I would have to choose only two: Digitakt+Digitone is the way to go! If you want to have keys, attach a Keystep to it! The combo totally rocks! You have everything that is possible with the Digitakt and a phenomenal Soundengine in the Digitone. Synced together, they work really great and if you want to attach stuff later on, you have 12 Midi Tracks.
Why not the Minilogue? I love the Minilogue. Its a great Synth, and I use it all the time, because it sounds great and is easy to use, but at the end, most of what I archive there I can archive with the Digitakt and some time too. Single Cycle Waveforms and the Digitakt together with resampling play were well together. Want a fat bass synth? Search for Moog Samples. There are some without unfiltered unmodulated samples out there, that sound amazing with the Filter and FX Section of the Digitakt. And for my opinion: 4 Tracks Digitone with the PLock Functionality outweights the easy to use approach and the accessibility of the Minilogue!