Win over kills, always.
High kill loss always feels terrible. A win always feels great.
How great the win feels highly depends on the path it took to get there and number of kills is really not even among major factors.
Run with no gun for 5 minutes, escape 4 confrontations, finally kill some1 with a mozambique for his basic loot, run from the zone frantically and use all meds for it just to run into a fresh drop with a mastiff, get ambushed instantly and survive, devise a masterplan to 3rd party the last teams and succeed - that would be a one epic win (with just 2 kills total).
Similarly, a 15 kill win could also be epic, or it could be a major meh too.
Doesn't mean I won't go chasing kills, if I'm certain I have massive advantage XD. I'm still not a fan of taking fights that I think are not increasing my chance to win.