To be honest I can't really remember when I first came to TV Tropes, but I didn't really join until recently. As for why I joined, well I suppose I wanted to make a trope list for a couple of fanfictions I liked, which is one thing which drew me to TV Tropes: the fanfiction recommendations.
As for myself, well I suppose I can say that I'm drawn to stories that aren't black and white probably because its easier to relate such things to reality (for the most part). There are no absolutes in reality after all. Favorites fictions and all that...Legend of the Galactic Heroes is one (Code Geass is a poor shounen expy IMO) for anime, along with the UC timeline for Gundam (apart from G and Turn A I can't like the other timelines), while Macross is always good due to its music. The same goes for the Vision of Escaflowne, as for manga my favourite is Claymore and Ah My Goddess (yes I'm a guy, but to hell with that). Non-anime...I like High Fantasy novels, and while I don't mind vampires, I'd rather go with the classic, old school vampires rather than the 'sparkling' ones these days (shudders). Video games...preferably RTS or First-person Shooter, but I also play RPG. Command and Conquer, Halo, Shin Megami Tensei...well there's too many to list.