Formal:
* States
* Declares
* Affirms
* Indicates
* Maintains
* Argues
* Posits
* Contends
* Avers
Informal:
* Writes
* Explains
* Thinks
* Believes
* Claims
* Suggests
* Notes
* Points out
* Remarks
More specific:
* Whispers
* Shouts
* Mumbles
* Grunts
* Moans
* Sighs
* Chuckles
* Laughs
* Cries
Figurative:
* Proclaims
* Announces
* Reveals
* Whispers
* Shrieks
* Boasts
The best alternative will depend on the specific situation and the tone you want to convey.