I need advice on upgrading my DVD player

I currently use A Denon 3910 in my HT 7.2 setup, Mac mc207 amp, anthem avm30, paradigm sig4 & C3 for the fronts. I am trying to decide if I can further improve the sound (movies mostly but some CD's and SACD's) with a player upgrade. Currently i want to stay out of the blue ray game. I am considering a Denon 5910, Mac MVP 871, Arcam DV139, Esoteric. . . Or is the Denon 3910 close enough to its bigger brother or the others to not warrant the expense??