That's a good question. Probably as a boy though. Humanity is higher than dragons.

Have to admit to a sneaking liking for Human Eustace, even before he changed. Though he was much better after the undragoning. What I like the best about him afterward was that he didn't instantly become better. He still had to struggle with his inclinations and prejudices. But the improvement was noticeable, and the only one who didn't like it was poor Aunt Alberta.

There's a lot to be said about how useful Eustace was as a dragon, and how that changed his perspective on life, but he was fundamentally a human boy and being a dragon didn't suit him. He probably wasn't even the sort of person who ever fantasized about being something other than a human.

So I'd have to vote for human Eustace, post-un-dragoning.

Human Eustace, but it was really fascinating to see him transform as a character when he was trapped in the dragon-skin. It's probably one of the most interesting and powerful Eustace-centric moments in the entire series. It's the first time he reaches out for help: from his family, shipmates and from Aslan himself. I also love how Reepicheep would talk to him. Even so, however, he was miserable in this form. I'll take post-undragoning Eustace any day, while also recognizing that the experiences he had while a dragon were what put him on the path to become the character that we know, love and admire.