I was about to buy an Elektron Digitakt II but stopped as I though that it may be too similar as Zynthian (MIDI Sequencer + Sampler) and refrained my buying decision to prevent GAS (Gear Acquisition Syndrome)
But recently, I came to this post showing both and I wonder if they can in fact be complementary:
if so what there is one not in the other?
poke @richardrijkhoff as its your setup, maybe you can add information and help me 
No answers, did I said something wrong? Or maybe I chose the wrong forum category?
Hi @Laura! Nothing wrong with your post. I guess we were all waiting for @richardrijkhoff to reply as they have the exact setup you are asking about.
My opinion would be to try zynthian Oram to see if it does what you want then chose extra kit as required. zynthian does have a flexible and capable sequencer although it isn’t as polished as some other devices. It can do a lot and there is functionality that is not yet exposed (or implemented) that has the potential to make it even more feature rich. The challenge is to present this in a way that benefits as many users as we can. There is a tendency for users to ask for what they already know, e.g. “Can you please make it do this because my favourite sequencer does that?”. I want zynseq to be its own thing. It is inspired by many sequencers that come before it but it is not them and some of the technical design is rather different. This means we have a sequencer that is its own beast and works its own way - something users must learn - just like any other tool!
zynsampler is similarly its own thing. It evolved from a simple audio file player to a complex sample player with loops, slices, pitch and time shifting, etc. Again, inspired by various other ideas, it does its thing but is also not as polished as other units. There was a lot of work done to get it ready to be a good tool but I would say it isn’t quite there yet. It needs more attention, particularly to workflows.
Something that is happening with our current effort to write documentation for Oram is that user interface and workflows are being described, tested and fixed. I think a similar operation for the sequencer and sampler will greatly benefit them. There is a fairly good zynseq guide which I wrote and @LFO updated but it would benefit from a refresh with Oram and sepecific workflows in mind.
So, I don’t have a Digitakt and can’t give any advice on it. I do have zynthians and various bits of (mostly old - like 1980’s) kit and like you, want to avoid GAS so I try to get zynthian to do everything I want and use my existing keyboards, controllers, amps, etc. with it. I want one box to rule them all, not least because it makes rehearsal and gigging simpler. So I am interested but sceptical of any other kit. I am sure there are fantastic alternative workflows and equipment - I want zynthian to do it all - but this is not true for most people.