8

I’d say that if you have the opportunity/money to get both, you won’t regret it. They don’t really overlap in sounds at all; their capabilities are quite different.

While you can definitely make cool percussion on the AK (and conversely, cool melodic sounds on the AR), it’ll take a lot more work. If you want sounds that are drum-like right out of the box, the AR is much more immediate for that purpose. The parameters of the various tracks are tailored to percussion synthesis.

Both boxes have sequencers. It’s nice to be able to mix and match melodic/harmonic and percussive sequences, and having both units will allow you to do that. Enjoy!