Mmmmm, that's a tough one! I'm still waiting for the best years of my life to happen.. but it's getting better!
I'd say 2014 or 2015, because my relationship with my ex was really nice back then, and we went to a lotta cons, and had tons of fun.
At the same time, I was still getting through lots of depression at that time, so it had good moments but it wasn't a good year, necessarily.
I'd say last year might've been my best year, pouring into the start of this year, because I was more active, and got closer to some friends, and made some new ones. Found of a lot of peace with myself, and my job, and things with my girlfriend were good, and I barely felt depressed at all. It was wild because I felt way more free than I had before. It was mostly due to inner peace, I guess. Things are a lull right now, but I'm pushing to pick them back up again. :>