OOOOOOHHH TOYS!!!!!!
I agree, the A1200 is the most advanced out of them all and is better suported with "new" hardware, so I'd build that to the max!!!
The A2000 will be a bit harder to upgrade as it's nicer upgrades are going at a premium. Nun-the-less!!! Geting a 030 for it and keepimg 2.04 ROMS in it will make it a very, very stable comp for old and non-AGA games/software... (Save the 3.1 stuff for the A1200)
GOOD LUCK!!!! :-D