Glossy seems to have more depth to the blacks for me- maybe this is just an optical illusion? OTOH, too much gloss can be a bad thing- I guess it depends on the subject matter.
Strange but true confession:
I also sometimes use carnuba wax on matte prints- I have gotten several positive compliments on the resulting surface- but it is a lot of work, and may not be archival? Anyone else ever tried waxing or am I a real weirdo on this one?