Prompt, thorough, and high quality people.
I have used A Quality First Plumbing twice this year. They have always been very prompt, very thorough, and communicate well with me as the client. They clean up after themselves as well.
Both times were great experiences, and each time I had the same service representative, Dave. I trust him being in my house whether I am there or not. One time they came for an overflowing toilet and the other time was for the kitchen sink. Everything works great now. They have high quality people, which makes a big difference.