Metal Gear Solid HD collection is the king of HD collections.
It contains two PS2 games and one PSP game.
The best of these three, in my opinion, is Metal Gear Solid 3: Snake Eater.
All of these games ported great from their original hardware, in terms of gameplay, graphics, and sound.
Peace Walker, though a great game, looks a little chalky at moments.
Snake Eater looks the best, being the newest title.
And Sons of Liberty's graphics are somewhat in between the two.
Peace Walker and Snake Eater have almost exactly the same controls, since both are newer titles.
Sons of Liberty was a little challenging for me, due to the fact that you cannot move the camera and there is no objective map. Though, it is perfect for gamers wanting a bit of a challenge.
This game is completely worth a buy, and definetly a rent if you're a little tight on money.
In conclusion, this is the best HD collection out there.