"The Best"
A1200 for me, followed by the A3000.
"Favorite"
Varies from year to year... :-) Right now my A500 project. From a technical perspective it's not the coolest amiga, but I'm having fun. I'll have a few pics in the photo gallery once I get the case for the GVP A530 repainted. I'm surprised at how much faster/more responsive the SCSI controller is over the A1200 IDE (suXXorz).
Next project will be an A3000, if I ever get the time. :-(
"Worst/least favorite"
The A2000 is the WORST amiga ever, I dunno why any sane person would like that model :-? We had one at our high school, every time I walked by it I thought "what a piece of crap, why don't they buy a real computer"