For years I used Aspen Creek Photo, based in California, to make my prints. I tried many other print makers before deciding which one to use. I developed a preference for Fuji Crystal Archive matte paper, which is very similar to what many inkjet paper companies sell as satin photo paper. ACP uses Fuji photographic papers and provides a very professional service. However, they offer a limited range of products, specializing in high-quality photographic and inkjet canvas prints, at which they excel.
I printed mostly 8x10 and 8x12 prints because they sell well in our frugal community, but many larger ones as well, up to 16x24 and got very good results. My camera is a 12 MPixel D300. Aspen Creek Photo provided very reproducable prints.
As for other print makers, I found Adorama in NYC quite reliable and inexpensive, but they use Kodak paper. However, they do not provide a really "professional" service, more of a consumer service. White House Custom Color has a good reputation. They are a full-service print maker, offering many types of products; they use Kodak Endura paper.
The earlier comment about the importance of good editing of your image files is spot on - I never let any of the print makers adjust my picures, I felt I needed to control what the image looks like.
With my new Epson Pro 4900, I am presently not using Aspen Creek Photo, but can wholeheartedly recommend them.