I haven't played battleborn, so I can't comment on it.
But Overwatch is the first online multiplayer game that has caught my interest in years. I normally don't go for online multiplayer, hell I only played League because my friends did and when they stopped I had no desire to continue.
OW changed that. It's the first Multiplayer only title to actually catch my attention and make me legit feel like I'm having some kind of low-level withdrawal symptoms after having a blast during the 2 days I got to play the beta (I was just really getting into the groove of it when it ended.
I wasn't ready for a break!)
It's TF2 with superheroes, where while skill is important, there are lots of ways to be a credit to your team without needing to be a flawless headshot pro at 80 feet. And the variety of hero playstyles, each one fun in their own way, really just sells me on it.
I'm very stingy with my money these days, but this was 40 bucks I was willing to drop like *THAT*. I don't know how I'm gonna get through the next 12 or so days to release.
EDIT: Also, I LOVE "play of the game" and the fact you can swap heroes mid-match. It encourages you to mix it up and adapt your strategy, and I love seeing amazing plays at the end of a match. If it's an ally, you can appreciate what they did for you. If it's an enemy you can go "Wow, that was pretty good. They kinda deserve that win". And if it's you, you get to bask in your own glory for a few seconds. It's great.