I want to love Xbox One. I really do. As you said, the controller is almost perfect, Xbox Live is leaps and bounds better than PSN, and certain things seem to be integrated more organically than with Sony. Unfortunately, unless the majority of your friends also have Xbox there aren't many exclusives that knock it out of the park. Forza Horizon 3 is my favorite Xbox One game and has been since its release. Halo 5 is good but if you've waited this long to get on the Microsoft train, it wasn't a draw for you in the first place and there's no harm in waiting for Halo 6. Same for Gears. Sunset Overdrive is funs for a bit. Some people absolutely love it but I thought it was good, not great. I'm sure I'm missing something. Regardless, Xbox's exclusive titles can't hold a candle to PlayStation's. Like you, my main wish is that they clean up and speed up the UI. I have faith in the system and where they're going since Phil took the reigns but it's going to require a lot of patience to get there.
I've had a 360 forever but never played Halo. I think I got one of them for free at some point. Who knows anymore.
It's hilarious that the only thing I've done with the new machine so far is play old 360 games I've had for years and ignored. Though to be fair I tried playing Rock Band 4 tonight and I'm now in the middle of an 11 GB update.
I'm not a fanboy but have mostly enjoyed Xbox over PS on the previous consoles. This time though, Ps4 is the winner for me. The only game that I've played exclusive to Xbox is Gears of War 4.
If you like the franchise it's one to get. Honestly though, it's my least favorite of the bunch. I rate it lower than Judgement Day....it has some good stuff but it's also the first Gears game that I had no desire to go back and play after beating the story and leveling up in multiplayer. It's just more of the same with little enhancements to keep me interested.