Over the last year, ACIV: Black Flag on PS4 outsold the X1 version by about a 2:1 margin. I think a lot of that had to do with the PS4 version looking slightly better. 

However this year, like it or not, there's parity between the X1 and PS4 versions of AC: Unity.

Not only that, but the AC Unity Bundle for X1 is pretty aggressively priced and marketed. 

However, PS4 does have the advantage in already having a much larger userbase. And during the time PS4 wrapped up an early lead with ACIV during the holiday launch, PS4 and X1 were more competitive than in prior months summer doldrums.

What version do you think will sell best? I for one get the sense AC Unity on X1 will outsell the PS4 one this year.

Even though PS owners are hating Ubi for 900p I think it will sell more on PS4. US most likely X1's though.

I agree with jlmurph2.
Ya Europe will help push PS4 over. Userbase lead helps a lot.

Unity will sale more on PS4 in NA, Europe likely 4-1 ratio.

Higher user base and not a fps, PS wins.  

Nope. PS4 userbase is against Xbox One. Plus third party games sells more in PS4.

Dear lord no. Last gen the PS3 versions ended up beating the 360 versions (after AC2). With the PS4 userbase advantage it won't be a contest. I don't think many (or any) big multi-plats will sell more on X1 this gen.

PS4 have the bundle and advertise last year.

This year looks like Xbone will be the edge because the bundle in US (after CoD I don't believe anymore in UK).

WW will be PS4.

Globally, no. In the US, maybe, but I still think PS4 will edge X1 here. The user base is much bigger so all 3rd party games will sell more.

We could compare it with CoD, that's a game that receives exclusive marketing and bundling for years. Even being a much more favourable situation for X1, it can't make for the sales difference.

AC 2 was the last one i played, probably won't pick this up. That being said it seems pretty obvious that PS4 will sell more WW.

Expected Toastboy...first time I've been wrong.