Hi Doc,
Welcome to ED. As other people have already stated the games are the same and I play the game on both (yes I am probably a bit mad!!!) so am in a good position to give me some advice.
Currently I play the PC version as the XB1 version currently has some really bad speed issues particularly in the game menus, which have become really frustrating of late (which the PC version doesn't suffer from, at least not on my PC (Its an old PC which I built myself but has been upgraded a tad for ED (AMD Phenom II X4 965 3.4ghz processor, 8GB Ram, Samsung 500GB SSD Hard Drive, Samsung 500GB SSD Hard Drive just so you can have a comparison to your PC, I limit the game to 60FPS which I get throughout the game))
However saying that, when the XB1 version gets fixed (I do have faith that FD will sort it out, the issues only seem to have been introduced in 2.2) I will go back to it. The community is much better on the XB1 imho, everyone if on a level playing field and I prefer playing on my console.
Regardless of which you decide to go with, its a truly fantastic game. I play lots of games but ED is always the one I come back to.
And to answer the question you actually asked

Yes there are more players on the PC as it was initially released on the PC, however there are a large number of players on the XB1 too. I wouldn't let the number of players on either sway your decision to be honest as there are plenty of players on both platforms for private groups, open interaction and winging up etc (I cant comment on CQC as I have never played it and probably never will

)