Best looking Amiga? The 4000 (desktop) with the 2000 being a close second.
Seriously, it's all about the 1000. I still get at tingly feeling when I look at it. It's a simple design that somehow manages to look powerful and still warm and inviting. Look at IBM designs from that era; they look like trucks.
I didn't care for the 1200's 'wedge' design the first time I saw it but it has grown on me over the years and now I rather like it. It looks the most current of any Amiga largely because it's white rather than beige. I've had a few people notice my 1200 and ask me what it is. That has to be worth something.
P.S. I was most disappointed by the design of the 4000. It's an abomination.