1.) Howls Moving Castle
This movie made me a Studio Ghibli fan. I had only watched Princess Mononoke and Laputa: Castle in the Sky before then but Howls Moving Castle is the best one. Best animation, best story, best characters. I thought it was better than Spirited away... speaking of which.
2.)Spirited Away
I just watched this movie about a month ago for the first time. I liked the characters but the plot dragged compared to Howls Moving Castle.
3.)Laputa: Castle in the Sky
I loved this movie. The characters of every Ghibli film make you fall in love with them. They're so vivid and alive that you don't even feel like you're watching an animated film anymore.