For me, I love that the Xbox lets you do things like play certain games on your PC if you have them on the console and they support cross-play. And the backward compatibility for my old 360 titles (I have every single 360 game I ever purchased still) is a big winner as well.
I also looked at the exclusives on the PS4, and to be perfectly honest, there aren't any that I particularly feel that I'm missing out on from the past, aside from Spider-Man which is a new release recently, and then perhaps Ghosts of Tshushima. Many of the PS4 exlusives are indie titles or Japanese titles that I really have no interest in playing. I do intend on getting a PS4 at some point, but at the moment that's on hold and I'll be upgrading my TV instead (I only have a 720p TV for use with my Xbox atm!).
Oh, and GamePass, which is a breath of fresh air, especially when you've managed to bag yourself six months for £20 like I did. I've been playing Forza Horizon 4 recently, I can play that on my PC using GamePass as well, and there are a few other games on there that I've had some fun with recently as well.