What I want most is the content design in regards to gameplay to break out of the predictable pattern we've seen in recent expansions and and be more creative and way less conservative. Mainly we need new gameplay mechanics, things that make us play DDO differently. Story, monsters and quests looking good visually and all that is good and all, but what we need most is new video game things.
I often feel in regards to content design in recent years is that in an attempt to appease all players into not hating a quest they've all been watered down to feel the same and be too basic. It's OK for everyone to not like every quest. Cater quests to different player interests. I'd much rather have out of 10 quests there be 2 I hate, 5 I feel OK about and 3 I love rather than it just be 10 that all feel only okayish to me. Take chances in content design devs, please be OK with not everyone liking every quest.
Mobs with unique combat mechanics - Pilgrims Peril was a good start to what I mean here. We need stuff that makes us think more about encounters and play differently.
Brand new puzzles from the ground up - Not just slight minor alternations of the same old puzzles we've had a million times. This has been a big stickler for me. I am so sick of the same old tile puzzles, light puzzles and mirror puzzles being rehashed again and again. How about a card game we play in game? picture slider puzzle? Optionals that include complex, randomized cornfield like mazes? There's so many possibilities.
Platforming optionals - Some kind of crazy difficult snowpeaks esque platforming optional. Emphasis on optional, it should not be a requirement for completion. But personally I love platforming in DDO and we never see it anymore. This goes back to what I said initially about taking chances in content design and being less conservative - it's OK if not everyone likes every single aspect of every quest.