Brother buying Christmas present

So my brother is willing to buy me a Christmas present, with the limits being $50. What do you guys think I should ask for? I don't really have much, but I just thought that if I asked for something like a PSP or PS3 game, anytime my friend came over I could play them. So I was thinking of these:
1) Birth by Sleep (of course)
2) Crises Core
3) Final Fantasy XIII
4) Dissidia (first or second)

Which of those do you think I should ask for? Or if I should not ask for them at all and just try to find something else that I can actually play?

 

I would definitely go with Birth by Sleep.
Looking at some gameplay videos, it looks really interesting.

 

The second Dissidia not that first. the second has everything the first has and even more

 

I would, Like KH530 said, go for the second Dissidia. I think you'll get more hours of quality entertainment from that.

 

i think i will go with "birth by sleep" i think that game could be amazing