That's a tough one...
I currently own thee Amigas: an A1200, an A2000 and an A3000. I had an A500 back in the days (1988, I guess), but my current machines are the ones I wanted the most in the late 80-ies/early 90-ies.
If I háve to choose, I think my most favourite Amiga is the A2000: easy to expand and easy to replace defective chips.
If you ask me again next week or next month, I might as well answer 'A3000' or 'A1200' then, though.