Maybe others will chime in w/ other cool positives.
Unique look. The 919 always gets double takes from cagers and riders, especially because mine is gloss black which everyone knows is the fastest.
Super comfortable yet easy enough to get into a tuck for the twisties.
Great motor with always-available power from idle on up.
Nice handling for a bigger bike.
Harley-guy always waves because of the big round headlight, the lack of plastic and the confusion that the bike causes.
Sportsbike-guy always waves because they zoom in on the cool tank and the exposed inline-four plant.
It has character. There are some classic elements and modern elements that really work well together. Sure, the look is somewhat dated but it's awesome.
Great value. It's a hell of a bike for the price.
It's a hell of a lot of fun to ride and really versatile.
So, I'll take the stink to have all that!