I like them all :-D
The A500 was the first one I had but lacked HD interface... that made me buy an A1200.
The A1200 is Ok if you don't want to expand it much. When you start to add cards it turns into an unstable sandwitch of custom cards. You have to replace the PSU... well, with a 030, an internal 2.5HD and a PCMCIA network card it's nice, but putting it in a tower makes it butt-ugly.
The A3000... well, it's certainly not for poor people. I almost switched to an A3000 years ago when I was a student and had no money. But soon I realized that I had to invest *a lot* to put it in the same level than my previous 1240/25... I had to buy expensive ROMs3.1, expensive ZIP-ram or expensive SIMM adaptors, expensive graphic cards to be able to see more than 16colours... and if you wanted something more than a crappy 030/25 or 16Mhz like mine, you had to buy an accelerator. The A3640 was crap but the cheapest one for A4000. For A3000 you may have endless problems with it so it was better to buy an accelerator with ram sockets and maybe scsi controller, as the onboard A3000 scsi isn't marvellous. The A3000 case is beautiful, but inside it's a mess: you don't have space for 5 1/4 devices and dismounting it is a nightmare. It doesn't have IDE for cheap HDs/CDs so if you wanted a CDROM you had to buy an external case! (that's ridiculous being a big box amiga, isn't it?). The PSU is quite weak too. So I went back to the A1200. Now that I work and can buy stuff I have an expanded A3000 and it's very nice and stable, but in the long run it's much more expensive than an A4000, offers less expansion and more problems.
Later I came to the A4000. It was a dream come true: AGA, stability, expansion, a beautiful case with enough space inside for 5 1/4 devices and up to 3 HDs! Simply cool! It was a pity that it could only be expanded to 16MB. It should have come with a jumper to boot in 31Khz modes as default so if you aren't into demoscene or games you could cold boot and see early menu. Or even better, an scandoubler.
Later I got the A4000T... it's clearly the best of all amigas ever produced. The case is big and allows airflow, it includes decent scsi controller and also an IDE interface for cheap HDs/CDs. More expansion than any amiga, an standard motherboard form factor for the first time in the amiga history (It's an standard AT board). Simply great.
The worst model would probably be an unexpanded A500+. It has compatibility problems with games but no HD interface or pcmcia like A600. But I like all the amigas produced. They are all special.
