Well, A3000 are better in terms of Z3 slots, built-in flicker-fixer, and socketed chips (if one breaks, simply replace it).
A1200 is cheaper and expanding it will be cheaper. No Zorro slots, surface mounted chips (one breaks and you are in need of a new mobo, most likely), however features AGA display and built-in RF modulator, unlike A3000.
If you don't care about AGA demos and games, then A3000 is the way to go, by all means.