This also depends on your importances in using the machine. If you're in love with tweaking hardware and de-coding crashes the above advise is all to the good. If you enjoy cussing about freeezes and crashes, they're riught on the money.If you care more about using a computer to get work done, I'd say go for a used G3 or G4. I have a dual-processor G4 just now which I am delighted with and it runs like a racehorse day in and day out.
Reliability is important to me. I hate having to invest my time in fretting with IRQs and mysterious settings.
That's why I use a G4.
A