For xbox 360, Should i get halo wars, call of duty 4, or GTA IV?

[sk8_221]

i have a PS3 too and i have COD4 for it but i have my friends on xbox and i cant trade in the COD4 because my dad plays it a lot. So yeah Which one should i get??
I already have COD5

 

[kyle]

wait to get modern warfare 2. going to b great