I own a PSP-3000, never used a Go.
If we talk about pricing, a PSP-3000 + 16 GB MemStick > PSP Go. A GENUINE 16 GB Memstick for PSP-3000 costs around 70 bucks, so you see the difference.
About quality, I state the same again, never tried a go, but buying a PSP over 2000 is the best you can do...