When I printed for work I had good relationships with bayphoto, millers, whcc, and h&h color. Disclaimer this was like 7 years ago but I don’t know why their quality would have changed in the meantime.

I haven’t yet but I am going to print some stuff from mpix. I heard that they do a great job from a few professionals that I have talked to.

I have used mpix and found them reliable.

I prefer to do my own though, when I do print, which is rare.