Tanks in LoL

Im starting to try out some tank characters in League Of Legends. My favorite so far is Mordikieser (or something like that). I like him because he has passive armor and he can do a lot of damage too. Some other tanks ive tried are Ramus and Cho'gath. I think tanks are really important In LoL whereas they are not too important in dota. I think this is so because, in dota, when you gain agility, you gain armor and attack speed. But in LoL armor is gained from items, so you cant be a tank unless you buy certain items. I recommended trying out a tank if you like to be in the middle off battles and not be afraid to take a lot of damage.