For me, my favourite types are:
Water - I've always liked the ocean and the soothing sound it makes. Makes me wish I actually lived near it.. D: I also mostly like the Water Starters, save for Mudkip of the 3rd Generation, which was replaced by the Fire type, Torchic, when I played through RSE.
Ice - I really love Winter, and snow is situated with Winter.. and with cold weather comes ice! XD I really like the Ice type for that, and not to mention, Glaceon is of the Ice type, as well.. <3
Fire - Fire types are really cool, and though I love the cold, I fell in love with Flareon, when I saw it.. <3 On top of that, it also has Ninetales, who is another nice Pokemon. ^^
I really hate hot weather, though, so.. I call strange on my liking the Fire type.. XD;;