I voted, why did I need to respond?  

You haven't seen all the timed exclusives Sony is doing now?  Maybe not for a year like this, but a lot of em' exists. 

also note that x360 version launches alongside x1

Xbox 360 version

On what planet do people think Tomb Raider will sell more on Xbox One than on PS4. I mean...seriously? By the time it comes out on PS4, Sony will probably have triple the amounts of consoles in the wild than the Xbox does at the time Tomb Raider releases on the MS platform. Tomb Raider  already sells more historically on Sony platforms anyway so I see nothing to suggest a change here even if it does release a year later.

Xbox One

Don't forget that the XB1 version will most probably have a 299$ bundle (including TRDE) with a 2 months temporary price soon to be permanent.

X1 will have a year and likely a price drop or two before PS4 version comes out. I wouldn't doubt it is at $20 by September of next year at several stores. The install base difference and history of the series will help make it close, but I cannot see PS4 version making up the gap unless it is $20 day one with added content.

when will uncharted 4 release?
couldnt it kill tomb raider momentum?

Initially PS4 seemed like the obvious choice just by the number of consoles in the hands of customers, but...

the game might be mediocre so buzz might not be there anymore.  

I doubt SE will have the marketing budget to push it next year.  

The game will most likely be going against stiff competition next Holiday.  

It will have a year head start on the XB1.  

So... PC.  

I mean XB1

I'm going with the PS4 ( When it reaches $3.99 on PC though, just like the previous Tomb Raider, we all know where it's going to sell more ) due to an increased user base and since PlayStation is generally known as the home of tomb raider.