The most important factor when choosing console are exclusive games. You should look at what Xbox has and at what PS4 has and then pick what suits you best. Don't compare tech specs because they don't really matter with consoles. If you're going to play online with friends, buy the same console as your friends.
On the side note - you should not compare PS4 Pro and Xbox One S. These are not meant as a competition.
PS4 Classic = Xbox One Classic
PS4 Slim = Xbox One S
PS4 Pro = Xbox Scorpio (not yet released)
If you own 4K TV, it might be worth it to go with PS4 Pro because it's the only one that has some kind of 4K support. On the other hand, PS4 Pro lacks 4K Blu-Ray support which Xbox One S has (not Classic!).
Here's what I would think about in order of importance
1. Exclusive games, which ones do I prefer?
2. What most of my friends own? (if I mean to play with them, else skip it)
3. Do I own 4K TV? (if yes, PS4 Pro)
4. Do I want to play 4K Blu-Rays? (if yes, Xbox One S)
5. Is there some great sale for classics?
I have bought PS4 in early 2014 when it was still hard to choose between PS4 and Xbox One as there weren't that many games. I'm really happy with my choice because Uncharted, Until Dawn, The Last Guardian, The Last of Us were really great games. There's nothing on Xbox side that interests me. Tomb Raider hurt me but now that it's available on PS4 and I have played it, it turns out it's quite mediocre and certainly worse than Tomb Raider (2013) and Uncharted 4.