A3000 and A4000.
The A3000 is basically the pinnacle of development with the least amount of cut corners.
The A4000 is the best AGA machine.
Amigas without true Zorro III slots are not worth my time.
Between those two, I would choose the A4000 if expansions are allowed (Indi AGA, CSmk2/3 060 + SCSI) and the A3000 if they should be kept stock.
Incidentally, I have both kinds of machine, the A3000 has as much motherboard and Zorro II RAM as possible + a network card, the A4000 has the turbo + scsi + indi aga and a network card. :-)