I have a pc and xbox one. Recently sold my ps4 to fund the xb1s. Pc is a 6700K/16GB/1070. I bought an xbox one because there were no more exclusive PS4 titles i was interested in. Played driveclub, tlou, bloodborne, until dawn, uncharted, infamous, killzone etc. I know microsoft are bringing a lot of xbox games to windows like forza, halo, recore, quantum break, horizon 3, gears of war which is great but i bought the xb1 to play halo mcc, halo 5, and some 360 games i had lying about like fallout 3/new vegas, skate 3, red dead redemption, halo reach.
None of those games are on pc except fallout 3/nv. I have them but couldnt be bothered with the hassle of fixing them to get them working. You could also argue halo 5 is on pc but it's not the full game. No campaign and not so great multiplayer. Maybe when they get around to adding a server browser.
So yeah there was a reason for me to get one. Maybe not for you.