I find 2. Ra6# (or Rh2#) more aesthetically pleasing, following ...Ka8 (...Kh1).
what's more elegant, a discovered check mate or a double check mate?

Mate is mate no matter how ugly
Aesthetics count, too.
I'm sure you mean accountants?

I often take longer paths to mate to get one that I find more aesthetically pleasing lol. In this case I would say Ra6# looks nicer, though the bishop isn't necessary.
Double check mate:
Discovered Check Mate: