Previous bike was a Street Triple 675 R which I had for 3 years before switching to the 790.
When looking for a replacement I test rode quite a few different bikes and it ended up between the 765RS and the 790D. On paper the 765 is a better bike in almost every way, it's more refined, but after riding both multiple times, the 790 just put a bigger smile on my face every time.
I was looking for something different though and if I had been on a twin before I may have ended up with the triple as I fancied a change.
With all that said, both are great bikes, you're not going to go wrong with either.
Observation is the greatest source of wisdom.