Battlefield 4 player stats
Currently Online (24 hour peak)
Xbox 360 - 5,800 (8,800)
Xbox One - 13,000 (22,000)
PS3 - 18,000 (19,000)
PC - 24,500 (33,000)
PS4 - 28,000 (35,500)
Basically it's fine all most platforms. You will have a problem getting full servers on many of the premium maps on the X1 (it's the same with the more populated versions) and especially if you pick game modes that are not the most popular on these maps.
In general though you will be fine and it's worth it at that price. If you are choosing between the two games and you want a battlefield type experience get battlefield 4 because hardline is a cops and robbers game rather than you're traditional battlefield experience. I enjoyed them both greatly but preferred battlefield 4!
Edit: battlefield hardline has very few people online. Only 5,000 currently on xbox one so only the most popular game modes and maps will be active. Even on ps4 which is the most active platform there's only 8,000 online.
The premium content on there is probably like a graveyard. As I said still fun but it you will only chose one Bf4 looks the best bet.
