Good years for E46 are 2003-05. 2006 is the new model year and early 2000's have significant issues with cooling system, electrical system, etc.
Make sure the top works fine, but you never know. My power top hydraulic system failed 10 months after I bought mine. It is a complicated system and costs $$$ to fix. If possible, get an extended warranty by BMW only.
Manual 325 or 330 is fine. Auto 330 at least.