At the risk of starting a heated debate between fans of one brand or another (I left out Agfa, etc.) on purpose -- here goes:
Back in 1999, I signed up for Ofoto.com, which was then purchased by Kodak and renamed Kodak Gallery, for some time. They are out of business now, and sold their assets and existing Kodak accounts to Shutterfly.com
I remember when I was able to order some great looking prints, up to 20"x30" on Kodak Professional Digital Paper, and what I liked about the Kodak paper was that both Gloss and Matte finish had a sort of "dry", non-reflective feel and look to them, when you ran your fingers across the print.
It is hard to explain, but the coating was different between the two paper types, both to the touch and under a white light & loupe, Kodak vs. the Fujicolor Archive Paper that Shutterfly uses. The Fujicolor paper, even in Matte finish, has a slightly glossier texture/reflective offset than the Kodak Professional paper did.
Now I realize that it could be a lot of things in play here, the printers that Shutterfly uses, the inks, and many other factors, but just before Kodak Gallery shut down for good, I ordered 6-prints, (8x10s) of some high-resolution images/3-matte, 3-gloss and then after my accounts were moved to Shutterfly, I ordered the same prints again, and compared them. The difference is obvious.
I can't say that I prefer one over the other all that much for the smaller prints, but for larger prints, it may be a sticky issue for some people.
I'd like to hear your thoughts and preferences.