You should definately get Gravity Rush. Why? Because its something new and exciting. MGS Collection? Well yeah, collection, they are ports of games you have probably already played and beat tons of times.
Resistance? Well yeah, its pretty buggy right now, and resistance isnt all that good IMO. If you want a sort of watered-down version than its console predicessor, by all means get R:BS.
Or, you could go with some new game that has entirely new mechanics, something that you never tried before, Gravity Rush.
I also suggest you look into Rayman Origins, its one of the most fun platformers I have ever played, and it is very lengthy. Trophies are moderately hard to get, and if you are a fan of platformers it is a must-buy. (though i know it wasn;t on your games-to-buy list).
It also is slightly better then its console version because it has more trophies are "Artifacts" you have to secrely find throughout the levels. (Collect them by tapping the touch screen, which is why PS3 doesnt have these).