Since when I became an Howl fan? To be honest, when I first saw the movie he didn't caught my interest at all. In fact, the one I really liked was turnip head! But since I watched the movie when I was what, maybe eight years old? I didn't like grown men that much, so it was normal that the heart stealer hadn't caugh my eye at all. (BUT turnip head is still one of my favorite characters of the show too).
But I grew older, and I became moooore interested in many male characters when I watched cartoon network in the night. 
Rewatching the movie when I was fourteen years old, now it was the time to grew a little attached to the wizard. I loved the relationship with Sophie, and even if his dramas about 'not being beautiful' some made them stop liking him for being superficial, for me it was a weakness he finally showed. And we all thought he was some type of perfect man with a beautiful face, but not even Howl himself was sure about him. It may come as ridiculous, but since I have some lack (or very much) lack of confidence about everything about myself, I could relate to Howl and Sophie struggle. These struggles, in my opinion, made them more human. 'But that is just a lame struggle' some may think, but it's the daily struggles some people face every day, and it can be really hard to accept one self, even when other people say otherwise.
i like howl a lot. he's such a dork— even when the witch and the queen's dog came along with sophie, he didn't even looked worried, even calling them 'friends'. he was going to sacrify himself for everyone, and that's what made me fall in love with this sweetheart.