Roland Tr606, esp combined with 101 has been a long standing favourite of mine. It really gets to the basics of rhythm/pattern creating and is often a good basis for building something very quickly. And those hats…so nice.
I recently bought the Roland R8. That machine is incredible. That sound and movement in pattern is very unique and it immediately sounds amazing to my ears.
I also bought the Rytm Mk2 and am super impressed although unlike the 606 or R8, it has raw starting points for sound, which seem very weak and uninspiring by comparison, although this is exactly what is needed for that machine. It’s a solid default stating point where you can unlock great sound through its internal sound processing. Having said that, I am finding the internal synthesis is better served supporting samples in many cases. I’m finding it really comes alive when sampling the R8 into it hahaha, which obv slightly sidesteps the issue, if you can even call it an issue…it’s not.
I am still exploring the Rytm mk2, it’s not super complex but finding your configuration or preferred sweet spot might take a while, it is for me. Both trying it totally out of the studio to get my head into the machine itself, and then bringing it into the studio workflow has been a slow but extremely beneficial way to tackle it.
I think for something that can either give you quick access to your preferred sounds or samples, or unique timing, or a great live or studio machine due to its multiple outputs are all massive appeals to me.
The biggest challenge I am finding with it, is finding its secret sauce, which is often the case with much new gear/software. It’s great at most things and it’s easy to do most things, so finding that quirk in the machine can be a challenge. I think, and I’m still exploring it, that it exists in simple combinations, and not getting carried away with applying too much too quickly. Saving lots of simple sequences and sounds, building up an inspiring library, much like you have to with say the Korg Volca, seems to be the way to go.
So, if you don’t mind putting in time to explore your workflow and how to incorporate the Rytm Mk2, then it’s a no brainier. Plus your’e getting way more than just a drum machine.
If you want something that sounds amazing out of the box and a bit cheaper then I’d say check out the R8. Wish I had bought one years ago.
Something that sounds just as good distorted as it does clean and has hats/cymbal grooves for days, and super simple to use with triggering potential then TR606. I think I use mine in every studio session without fail, even if I don’t use the sounds. Trigger outs and simple step sequencer make things super fast and inspiring.
Or buy all three 
Good choice!