Which is better nitepr or cwcheat

Well, Nitepr is more user friendly, but cheats are much easier to find for cwcheat. As they are both hexadecimal, they are virtually the same thing, but codes for one will not work with the other. You can convert the codes with a converter.
With nitepr, you have to press the home button twice at the first loading screen when you start a game, or the psp will probably crash. But after that, all you have to do is press both volume buttons at the same time to get the menu up, but cwcheats requires you to hold select for 3 seconds, which means you cant do it quickly.

Im pretty sure you need custom firmware for them both to work, but I am not 100% sure about cwcheat, as I got nitepr first, and that did require custom firmware.

In the end, you might as well get both, only enabling one at a time from the custom firmware menu, changing it for the game you want to play.

And in nitepr, run nitepred (when in usb mode via pc, not nitepr in game) and change screenshot to note and screen. Its much better than down and square. Ive got about 50 screenshots of me draging soldiers in metal gear solid! (because camera controls are the up, down, left and right, and you drag soldiers with square).