I'd have to say the A4000 is my fav...
After a while out of the amiga scene I got a broken A4000 off ebay and spent time and effort fixing it up and then expanded it with many things... It was my first real amiga expansion project...
Runner up is the CDTV as it's a challenge to upgrade and get stuff working... I'm currently building a new expansion for it, which will hopefully work well

After that is the A500+... Mainly due to fond memories.. My 1st amiga was a 500+

The everything else an equal(ish) 4th

Although I do seem to prefer big-box amigas more than wedge ones for some reason...