Hm..after having watched the whole series...
Obviously, as many in this thread have allured to, the characters do act differently between the manga and the anime.
I think my choices would be:
For looks:
Fiore - as others have said, there is something sensual about her maid outfits
(mwah ha ha..) , and her voice in the anime supplements that, too...he he he he...
Chrno (true form) - ...he is a demon, with his demonic looks, what more do I have to say?? In the manga, the way he looks at Rosette...so well drawn! Reading vol8 leaves my eyes lingering on several of his frames...his eyes....
Azmaria (especially in the manga) - yes she has gorgeous hair...which looks very nice with ther wings of the Apostle and dark dress at the end of the manga. In fact, if anyone has read the last chapter of vol8, you can see she has grow up to be a very fine woman indeed..
For personalities:
Chrno (manga only!) - definitely a stronger character overall in the manga. Less overwhelmed by remorse and a stronger faith for Rosette (thus not just supporting her as his object of affection! Well, me thinkeths anyway...)
Rosette - you can't beat her will, 95% of the time...amazing. And the thing is her character is believeable despite her unbelievably strong faiths...well done the mangaka, me thinkeths.
For Ambiguous reasons:
Joshua (Manga only !!) - some of us knows how differently Joshua has turned out in the manga...!! I know he has the the look of a typical bishounen, but there is this picture in the manga of the 7 Apostles on one page. He looks..well...not bad there.
Elder - mwah ha ha...
as a physics student, I must support him for his technological achievements!! In the anime, the sword extending from the cross with holy text on the edges doesn't look that bad (lightsaber..??Noooo...) AND his goggles....!! I want one of those!!(I know I am sad....)
Many here like Deufo....but...he keeps pinching hair out of his chin..? Quite an annoying habit, me thinkeths...?