I didnt start going for trophies until about 3 years after I got a PS3 so my completion percentage is bad, I typically go for the the plat on games I enjoy and want to get extra out of them. I hate to boost online trophies and only have done it a couple times Split Second and Tomb Raider come to mind but both are a couple of my favorite games from last gen. Transformers Fall of Cybertron was a game I wanted to plat but left it at like 84% complete cause I didnt feel like boosting trophies for specifc MP modes.
I typically dont mind grind trophies as ling as I like the game. Rayman Legends plat will prob take me a few months total due to the Awesomeness lvl 11 trophy.
I have no problem walking away from a game though if the trophies will zap my fun from the game. UFC will prob fall into that category as Submission Season and Knockout Season requires 5 wins in a row by KO (not TKO) and Submission online against randoms. This basically requires a quit if you lose and even if you win but not by the specific way the trophy requires. These stupid trophies effect the online community of the game and I wont quit matches just to go for these trophies and get lumped in with the bad sports who just dont want a loss on their record.
Third person Single player shooter are my favorite types of games to plat.
Essay Pro