I would highly recommend Horizon Plumbing. Silvano, Jessica, their team and I recently worked together and completed a major project for over a year, and they have been a complete joy to work with.
I am the director of a human rights org that works on water access projects on the Navajo Nation, and needed a plumber to help with one of largest projects to date. We needed to do a combination of re-piping and new water heater and filter installations in 25 buildings, in addition to installing a flush valve at a special needs school on the reservation. (Take a look at what they helped do here: waterforsaintmichaels.org.) The Horizon team was extremely respectful, communicative and collaborative, and I am so lucky to have found them. (I should also mention that they were recommended to me by one of the heads of a large utility company, so they are known for their great work.)
To say that this project was difficult in the beginning would be a gross understatement. I originally was working with a different plumbing company out of Phoenix who basically left the school, me and my org. out to dry, and when I had to replace them I was very wary about how and who to move forward with. Silvano and his crew were a godsend and helped everything go smoothly from the first call we had to the final inspection of their work. They were a huge part of making sure that tens of people got clean, safe water and we are very appreciative.
There was good communication, fair pricing and amazing work, and I am so happy to have worked with such a great group of folks.