For personality:
* Flamboyance: This is the most direct noun form of "flamboyant."
* Showmanship: This suggests a flair for performance and attention-getting.
* Eccentricity: This implies a unique and possibly unconventional way of being.
* Extravagance: This emphasizes the lavish and showy nature of the person.
For style:
* Showiness: This highlights the visual impact of the style.
* Ostentation: This implies a deliberate attempt to impress with display.
* Gaudiness: This refers to a loud and possibly excessive use of color and ornamentation.
* Bling: This is a slang term for flashy jewelry and ornamentation.
For other things:
* Flair: This can describe a showy talent or skill.
* Spectacle: This refers to a public display that is often impressive or dramatic.
The best choice will depend on the specific meaning you want to convey.