Los Altos, CA
These guys are real pros.
They were initially recommended to my coop by a top engineerer in the neigborhood for some serious plumbing work (replace a major gas line in our building, fix some corroded pipes, etc). They delivered the most compelling proposal, they showed up when they said they would, and everything seems to be working flawlessly. Of course I hope we have no more use for them, because plumbing problems often come with big headaches, but I have added Dave's Custom Plumbing to my speed dial just in case.