i had watched lots before that, but death note was the first one that made me go 'hey, i should watch more anime'. the second one was bleach, i think...? it was still when i watched them on youtube, haha. with italian subs...
Mine would be lucky star, I dunno if it counts since I saw a lot of other shows that I consider anime now, but it was the first show I watched and thought of it as an anime.
Found some Yuno Gasai 10 hour video on youtube and checked the anime, since I watched Mirai Nikki I couldn“t live a day without at least a bit of Anime.