black outline create such a contrast that everything else looks pale against it. So yes, it's easier to read, but its internal details got lost. Imho, the outline-less sprite is superior.
It somehow require that the background is adjusted to the contrast of the sprite, that's granted. The pale blue shirt might bring you really hard time to that regards (in outdoor scenes, that is), and it would be worth to investigate more vivid tones so that your palette of lower-saturation colours available for background don't turn all greys.
If somewhere in a castle's interior such a character became lost on a detailed backgorund tapestry, I'd be tempted to add a shadow sprite behind her that reduces constrast of the tapestry nearby.