Positive and lighthearted:
* Happy
* Joyful
* Merry
* Bright
* Sunny
* Ebullient
* Exuberant
* Lighthearted
* Jovial
* Vivacious
* Optimistic
More energetic and lively:
* Animated
* Spirited
* Bouncy
* Bubbly
* Effervescent
Gentle and warm:
* Warm
* Pleasant
* Agreeable
* Genial
* Friendly
More nuanced:
* Content
* Blissful
* Serene
* Elated
* Thrilled
For a person:
* Upbeat
* Sprightly
* Hearty
* Hearty
You can also use phrases to describe someone who is cheerful, like:
* In good spirits
* Full of life
* Radiant with happiness
* Has a smile on their face
The best word or phrase to use will depend on the specific context and the nuance you want to convey.