All I will say is that I started out mulching and had an issue where voles got into it and chewed off all the support roots to one of my trees. Now I'm not saying there wasn't something I missed that led to the issue, but ever since I went to gravel (from my creek) I have not had a single issue. The gravel works just as well because it still allows water to pass and holds the weed barrier in place.
I've been mulching for 3-4 years on my trees since I can't always get there to water them. I have not had any issues. Like said earlier though, stay a few inches off the trunk. I also used moisture mizer when i planted them. This combination works well. The trees that are 3-4 years old the mulch has mostly broken down, debating whether to add more as these should have a nice strong root system in place by now. Most of the trees are standard rootstock, which should also help on that front with a bigger and deeper root system.
I use 10-year landscape fabric (4' X 4') covered by pea gravel to discourage mice/voles. Then, I take straw bales that have been out in the elements for a couple of years and slice off bricks of straw (4-5 " thick) that I place over the pea gravel. I have had no problems with rodents and water retention is great. Also, I use hardware cloth (15-20" high) around the lower trunk area and I place a 6-7' diameter cages around the tree using 3-4 t-posts with the bottom of the cage 18-inches off the ground (for ease of maintenance work). A little more work up front; however, I shouldn't have to do anything more to the tree (except pruning after 3-4 years) for the next 8-10 years.