After some thought, Draco from Dragonheart and Haku from Spirited Away. Though I don't remember Dragonheart completely because I watched it when a long time ago, I do remember something about the dragon having a human form and being able to give his heart to another to save them, and I know I watched that movie more than once. And technically Haku is not just a dragon, but he has a dragon form, so in my mind, he counts. I love his design and personality, plus the lore of him being the river's spirit.
There are other likable dragons, like Toothless, Saphira, and Mushu, but Toothless and Saphira are more recent and both of them are very tame dragons. And Mushu is Mushu. He's obviously likable but not necessary in a dragonish way. I think I haven't read or watched that many books and movies with the wild kind of dragons in them.
Thanks for the question, TY c: