I vote for just the AV board. It will be cheaper and I don't want to replace the driver board and CPU board if they are fine. If the AV board is bad, that's what I want to replace.
Also, by this point in time the WPC system was pretty robust. I repair games every day. I've never had the need to replace a WPC-95 CPU or driver board. I've always been able to repair them. The AV board has a couple chips that are difficult to replace and are getting hard to find. The AV board is also more likely to have issues due to the heat from the HV section. The AV board is what's needed to be reproduced at this point.