This is my opinion:
S3 - too big screen and too much power and too small battery for that power.
S2 - cheaper and there is many good ROMS out there, which you can install (MiUi and CyanogenMod example). It's kind of plastic, but good support and lots of apps.
N9 - cheap and very good phone for everyday using. Good camera, very hard shell and screen! Bad support from the nokia, but best from the users (talk.maemo.org)