As a player, I tend to prefer games with story where combat supports and is a tool to give focus to the storyline, not just hack-and-slash dungeon crawls. Important, and fun if done right, but should support the story.
As a DM, I tend to create a world, with factions and geographic features with some big world events, then set the players free to do what they want. Very open on what characters are allowed to do, provided a story reason can justify it, it is in character, and the rules allow it. I prepare a lot, but make my notes broad enough to accommodate the inevitable character quirks. Improv is good, but I punish metagaming. Completely detracts from the fun. As another note, I tend to prep very long games (anywhere from 6 to 12 hours), though I may be more busy than usual, and might try to shorten them
Been playing D&d for 6 years, fluent in both 3.5 and 4.0 (Though I /far/ prefer 3.5). Began DM-ing 3.5 about a year ago. Fond of sarcasm, dark humor, creepy jokes, interesting vocabulary, wit, intriguing plot lines, and novel character concepts.