By "original", I take it you own a non-UW Machinedrum?
If you need ability to use samples, then the Rytm obviously fills that need. (Or cheaper Volca Sample? or Digitakt?)
If you don't need samples, then think about using the A4 to get some analog drum sounds going.
If you need everything at once, as in playing live, synth, drums, samples, then I'd get the Rytm. A4/AR/MD.
If it's just for studio work, layering up sounds in a DAW as you go, then the A4 might be all the analog drum synth you need.
As for me, I own a Rytm. My second. Love/hate. Mostly love. But I wouldn't say it's something I need for my music. My style doesn't call for too much glitch or sudden change of multiple sounds. Yes, I'm P-lock agnostic these days I guess.
I don't play live, but I'm thinking about it. If I did, Rytm would be a keeper, no doubt. It can pretty much make entire songs by itself. The only thing I truly miss is very basic MIDI sequencing. Not a deal-breaker, but that would push it up into an indispensable live machine, for my style of music. Rytm plus one table-top synth (like a Nord Lead 2/3/A1) and some pedals would be all I would need.
That being said, if you don't need a polysynth for chords/stabs/pads, etc. pairing the Rytm up with even just a couple of things like the A4 or even a TB-03, Moog Mother 32, etc, something with it's own sequencer, would make a killer little combo. Well, I guess the A4 can do poly. So there you go.
If you are flexible as to needs and musical styles, then either Rytm or Digitakt will surely be plenty of fun in the end. A4 + MD + whatever you decide will be endless combinations of sonic bliss.
I guess I didn't help much and have probably only added to the confusion. Sorry!