Neutral:
* Replied
* Answered
* Stated
* Remarked
* Explained
* Added
* Continued
More informal:
* Went on to say
* Chimed in
* Pointed out
* Noted
* Asked
* Whispered
* Shouted
More formal:
* Declared
* Asserted
* Proclaimed
* Announced
* Conveyed
* Articulated
* Elaborated
Figurative:
* Cried
* Moaned
* Whispered
* Gushed
* Spat out
* Snarled
* Chuckled
To show specific emotion:
* Exclaimed (surprise, excitement)
* Muttered (anger, dissatisfaction)
* Grumbled (annoyance)
* Sighed (sadness, resignation)
* Snorted (disbelief, amusement)
* Sobbed (intense sadness)
* Boomed (confidence, authority)
You can also use verbs that describe the action of speaking, such as:
* Argued
* Begged
* Complained
* Demanded
* Insisted
* Offered
* Promised
* Threatened
Ultimately, the best alternative to "said" depends on the specific situation and what you want to communicate.