I would personally take the Mac II since I like those machines and need one for the collection.

I have a 4/600 PS printer and it works fine, a bit slow at 4PPM but works with just about any serial equipped mac and does 600 DPI along with having a low power use mode when on and not printing (there is no on/off switch). Can be upgraded from 2MB to 6MB of RAM but that is not common to find.

I have a G3 desktop (300Mhz 1MB RAM) they are ok but I prefer the Towers (have a 433 tower). You need to make sure that the ROM supports slave devices or you have fewer options for adding drives (unless you use an ATA card or SCSI card).