Ok! Both are killer machines. If you’re not already in the Elektron world then Digitakt is easier to learn. However Octatrack isn’t too hard, it just takes some dedication and time to learn all of the ways you can use it.
I own both and love both for different reasons.
Digitakt was designed to be more of a one shot sampling drum machine.
Even though you can sample loops with the most recent update, you’re limited to 1gig internal storage.
Octatrack is a full fledged sampler, utilising a compact flash card up to 64g for storage.
I use it for sampling 16 - 64 step loops, mostly from my Eurorack, as well as a mixer for other elektron machines. It’s the central hub of the setup.
There are many ways to twist, resample, chop and play what you’ve recorded within the octatrack.
There are 2 effect blocks per track on the octa where you can pick from filter, reverbs, distortions, chorus, delay etc.
It houses many effects but only 2 can be used per track, unless you use a neighbour machine which will sacrifice another track to add 2 more effect blocks to your previous track.
Many people prefer digitakt effects as they are more modern sounding than the octatrack fx. Personally I think both have excellent effects.
Octatrack offers an amazing delay per track which can also be setup as a freeze delay for glitching which is my personal favourite.
Delay and reverb on the digitakt are send effects, but sound great.
Digitakt also offers a dedicated overdrive, sample rate, filter, bit rate, delay, reverb and a master compressor all available per track.
Both have 8 tracks plus 8 midi tracks.
Octatrack has 4 inputs and 2 master outputs plus 2 cue outputs.
And the best of all, the crossfader!! Scenes are a super powerful part of the octatrack.
Digitakt however has the control all function which is also very powerful and a feature from the original machinedrum. Control all is a perfect way to create new sounding patterns from existing patterns.
Anyway… there’s always more to be said about either machine… but hope these few thoughts off the top of my head can help you make a decision.
Cheers!