Neutral:
* Outspoken: This implies someone who freely expresses their opinions.
* Vocal: This highlights someone's tendency to speak up.
* Frank: This suggests someone who is honest and direct.
* Forthright: This indicates someone who is straightforward and assertive.
Negative:
* Boastful: This suggests someone who brags excessively.
* Rambling: This implies someone who talks excessively and without focus.
* Garrulous: This describes someone who talks excessively and often about trivial matters.
* Verbose: This indicates someone who uses more words than necessary.
* Loquacious: This describes someone who is talkative and enjoys conversation, but may be seen as excessive.
Slang/Informal:
* Chatty Cathy: This is a playful, but somewhat derogatory term for someone who talks a lot.
* Motormouth: This emphasizes someone's tendency to talk constantly.
* Windbag: This is a more negative and insulting term for someone who talks too much.
The best euphemism will depend on the specific situation and the tone you want to convey.