For me it would be the 1200 I guess, followed by the 4000D. I still like the (relatively) small footprint of the 4000 case compared to the average PC case.
Having said that, I am still in awe of the A1000. I remember seeing it on "Making the Most of the Micro" on BBC 2 back in the 80's and thinking "Want one! Want One!!!". I like the keyboard garage and it had add-ons like the Sidecar and second floppy drive - Two floppy drives was still a big wow to me then! It just oozed of magical delights :-) I never got one and had to make do with my C64 and 1541. Ahh, those were the days...
Retro