Both will probably suit you. I use the MD for these genres all the time and am completely happy with it.

It’s hard to say which will ultimately fit you better because the AR is so new. First adopters are still feeling it out and I suspect it will be some time before the OS is mature. And each instrument has features the other lacks that at some point you may decide you want. MIDI sequencing, direct sampling, scenes … best have a look at the manuals and at least give a thought to this.

In particular, if you’re into multitrack recording, you may want to wait a few months if you decide on the AR, as Overbridge will be a feature you’ll likely want … it won’t be ready till the end of the year however.