I've been into anime since a kid but it's been on and off for while. So, to be honest, there's not much anime I've watched. I'm also pretty much picky so maybe that's one of my reasons, too. :P Personally, I think the greatest anime were produced in the 90's-00's so I find myself liking more of the old-school type anime. Though, now that there's more anime being produced and all, my opinion may change until I've watched them all (or most of them at least).
I try to watch different genres. The main ones are comedy and fantasy though. I like a few good laughs when watching anime so the comedy part is pretty important. Serious/dark-themed anime, I would still watch as long as the story is enjoyable and does not drag too much. Gore and hentai/ecchi-themes are also totally okay for me, I like the occasional blood and insanity. Shoujo-ai, Yuri, Shonen-ai, Yaoi/BL, bring it on! :'D ...But after a few shows, I realized I'm not a fan of the school-comedy-romance combination so that's one type of anime I try to avoid, unless it's really good. Animation art-style also helps me decide whether to watch the anime or not. I usually decide by watching the opening. If it's good enough then I will try it out. If it looks bad, maybe I won't touch it in the beginning but if I hear good reviews like the story is good, etc, then maybe I will watch it. Again, I'm pretty picky. :P I'm also addicted to seiyuu (voice actors) so I'll also watch anime if they have really good voice actors...
Manga I like, too. I read more shonen than shoujo, but I will read shoujo as well if it's interesting enough. I like comparing the manga and anime (if it has one) so when I watch an anime and if it came from a manga then I try to read the manga, too.
My hobbie other than watching anime/reading manga is...to draw. Anime-style mainly since I was influenced by it. Still working on a style since because I get influenced easily, my artstyle is not really...constant.