I’ve found the A4 mk 1 to be much more open to various sounds than the Digitone(though it takes a bit of work to get to those avenues).
The Digitone sounds nice, and it is more suited to harmony and the like.
Things like Analog synthesis lends itself to being more Mono-based(though you can do a lot with the Poly mode).
I might be the rare person to vote A4 mk 1 on this thread because I tried both and preferred the A4, personally. I found that, with the presentation of the DN, there are a lot of avenues that slip through the cracks considering Elektron’s decision to provide the user fixed ratios on the machine.
Meanwhile, the A4(while only four “voices” max(you can do some tricks with the oscillators to create chords with a single voice outside of poly mode) you’re much more free to create whatever weird twisted sound you may want to create(subtractive speaking).
The DN is nice and simple, has 8 voices, and midi sequencing abilities- if you chose this, you’ll probably be very happy with it.
The A4, though- the arp editor is much more fun to poke around with(currently)(surely Elektron are working for a way to make this easier to explore)(I would think). Nothing is simplified- Elektron may have learned from the A4 and with people selling them and rebuying them and selling again(but always rebuying) and thus created the DN so that people have a much more favorable portion of freedom than complete. But, the popular consensus of sound leaves a lot to be desired if you want to “get weird with it”. Control-All on the DN is good in a pinch and is an easy enough concept. But the Performance Macros on the A4 REALLY, REALLY can take you to another world(but they take a lot of thought to set-up). You also have much deeper control of the FX on the A4 than the DN- and the FX track has it’s own(p-lockable) track to sequence
If you’re committed to putting in work and not flaking out of your purchase in frustration, I’d recommend getting the A4.
If you want something that you can get good sounds out quickly or if you want to play keys or if you love popular FM sounds- get the DN.
(Disclaimer: I’ve sold/traded 2 A4s, and now possess my third, and I am considering getting another DN- because it DOES sound really nice- and I can fit it into my setup easily)
Edit: sorry for the novel