I also find Williams games easier to fix. No hidden levels of switches on the score motor. Switches seem to be larger and easier to adjust. I can purchase flipper links/plunger already assembled and not have to mess with the roll pins. Much easier to see and access the score reel switches. Many times free downloadable schematics are available.

In terms of mechanical design, I'll take take the Williams Ball Count and Player Unit steppers over the Gottlieb player unit. The out hole to shooter lane mechanism on Williams games seem to always work.. DC power pops/slings starting in '72.

Gottlieb had the edge on soldering though.