If you think about it. Nero was very much like Bellamy was to Doflamingo.
A fake member of the group. Both weren't officially a part of their respective groups.
Doffy treated Bellamy like shit, and Lucci disposed of Nero likewise.
Lucci was very different from the rest of the villains, so you can't really get tired of him but I think what you meant was Doflamingo had a side to him which showed empathy for those very close to him regardless of their strength. He always forgives his close members regardless of their failures as long as they didn't betray him, so in that regard yes Doflamingo was unique.