A few hours ago i've installed Workbench 3.9. There's something wrong with the icons (probably becous i'm running BlizKick to start Kickstart 3.1) but it goes fine on a Blizzard 030/50mhz accelerator. I'm using a Amiga 1200. If you gonna move the Amiga much and only gonna use it to surf in the internet, reading and writing text files, playing mod files then a upgraded A1200 goes fine. But, it can get pretty hot so you'll need to put something to hold it up a few centimeters from the table and remove the thing that covers the acceleration card under the Amiga. I realy do like the Amiga 1200...it's easy to upgrade some and is easy to take to a hack. But, if you want to put graphic card or CD then you have to put in a tower and do some changes the the Amiga case and put some cooling fans in it. Otherwise i would say the Amiga 4000 or the AmigaONE. The AmigaOS 4 looks great, smoth and fast in action! But, remember, if you changing from the 68k processor to a PPC processor, then it's harder to play the old Amiga games, and, it isn't possible to just put in a floppy and boot ém...
Edit: I didn't see your last post until a saw your latest post...i should say that the AmigaONE or a Amiga 4000 with a VooDoo card is the choise for you...and a PPC processor and some other stuff, but remember that it can be very expensive with all the upgrades so maybe a AmigaONE is a better idea...
But...i love the Amiga 1200...it's so cute and looks so good... :-D