Best opener I've seen: Exhumed - All Guts, No Glory
Best opener I want to see: Dissection - At the Fathomless Depths/Night's Blood... I can dream, right?
Best closer I've seen: Symphony X - The Odyssey
Best closer I want to see: Immolation - Close to a World Below - They always play it, but in the beginning/middle of the set, which makes absolutely no fucking sense. Ending with it would be so epic.