One more vote for the Classic and Classic II. I'd not hesitate to turn a duff one into a MacQuarium, whereas an SE/30 or Plus you'd put some effort into sourcing replacement internals to resurrect.

Yes, the SE/30 was a high end machine whereas the Classics were cheap low end machines. There are heaps of them about and they're more limited in their real world usefulness in the year 2011. That equals lower collectivity value. Which makes the insane prices they've been going for on eBay lately even more daft.

The Color Classic is of course just as hobbled, but it's colour, it's cute and it's easily upgraded, so we love it!

Cheers, Ben.