We switched from ParkSFO to Anza a few years ago and have never looked back. ANZA is more convenient if you are driving North to SFO from the San Mateo Bridge or peninsula and the website offers cheap reservations ($11/day plus tax). The shuttle is always waiting at the lot and we never have to wait long at the airport when we return.

In the old days you would get free valet because the lots were always full. Now it is an easy self-park as there are plenty of spaces. IMO the only downside is getting to 101 South after you exit the lot. But you make it up on the front end vs. ParkSFO.