Okay I have a ps3 so I'm a little irrelevant here, but if you're looking for a reason to get Xbox One, here's three I can think of:
1. The ecosystem could be a big deal. PS4 would be a great console for you (so it seems), but you may regret PS4 later down the road if MS steps up and gives Xbox better integration with your other MS stuff. Not saying this would happen- and I don't know what exactly they would do- but there is definitely some potential. I had something similar happen to me in that I got my ps3 before I was heavily invested in the MS ecosystem, and now I wish I would have bought a 360 instead (I'll probably be getting xb1 sometime this year though). If you buy a PS4, you may loose out on some integration stuff down the road. I do believe MS will improve One significantly over its lifespan. Of course, integration probably wouldn't affect your core gaming experience, but you asked why you should get it to "complete my MS ecosystem"- and there's a reason why.
2. Titanfall.
3. I don't know where you're from, but if you're American, I would get the Microsoft product over Sony. Nothing against Sony here but it always ticked me off how Japan (or Korea, China, etc) is really dedicated to their national brands (Japan is PS4 territory), and the US seems to have no consideration whatsoever as to where their money is going. YES, competition is good, and YES these are publicly traded companies, but there is just something admirable about the Japanese's loyalty to Sony. It'd be cool if Americans wanted to support their home country as well. Try to factor in the brand and where it's from when making your decision (I kinda regret not doing this when buying my ps3...).