I started rpgs with D&D in the Fall of '76, the Greyhawk/Blackmoor/Eldritch Wizardy days (i mail ordered my first set of dice from TSR cause there weren't game stores around). I have played and/or DMed every D&D released, in most of the worlds they've released, as well as GURPS, RoleMaster, RuneQuest, Mythus, Warhammer, Burning Wheel, Pathfinder, and Riddle of Steel, to name but a few. My hands-down favorite ruleset is the D&D Cyclopedia. It takes those old rules that were so patched over that they were more about the patches and breathes new life into them, and thus into the joy and wonderment I remember. Its far from perfect, but it is fun, it works and it is fast. A lot of the other titles mentioned have so many unique and innovative systems that they collapse under their own weight. So, there is my two cents.