It depends on your use of the system.
If you want it for historical value, I'd do the DOS card (I have an official branded "Power Mac 6100/66 DOS Compatible", and it's fun to run the dual OSes,) whereas if you want a fast funcitonal system, the G3 wins, hands down.
If you want it for historical value, I'd do the DOS card (I have an official branded "Power Mac 6100/66 DOS Compatible", and it's fun to run the dual OSes,) whereas if you want a fast funcitonal system, the G3 wins, hands down.