do you mean an sr20de? if you do, it's a great little motor. but there's a lot of potential yet in the ga16de, especially with the hotshot turbo in development.
what to go with? it all depends.
ultimately, a turbo'd sr20de is gonna be the faster of the two motors (assuming both are turbo'd). but i'd just as soon go with a turbo'd ga16de over a NA sr20de.
on a side note, how much will the cams/heads run you? a whole new motor is quite an investment... but so are some of the new parts you're looking at. a good pair of JWT cams could cost you a pretty penny, indeed.
Swapping an SR20 is a lot more than just getting the motor too, you'd need just about the entire front clip from and SE-R or whatever JDM vehicle you might get one out of, including the tranny (not sure if it's included in the front clip). That's going to be quite a little bit of money.
did you guys see the $3,000 silvia sr20det build-up in SCC a few months ago? doing the same to a 200sx/sentra is gonna cost ya more than a few bucks. i guess it's sorta like the infamous honda b16/b18 motor swaps. hey, if you can afford it, do it. but make it a damn turbo, please!