General:
* Popular
* Favored
* Adored
* Cherished
* Beloved
* Respected
* Esteemed
* Appreciated
Informal:
* Cool
* Awesome
* Rad
* A good egg
* A nice guy/gal
More specific:
* Admired (for their qualities)
* Revered (for their accomplishments)
* Loved (for their personality)
* Celebrated (for their achievements)
* Delighted in (for their company)
The best word to use will depend on the specific situation and the person or thing being described.