Conversational is the most positive word.
All of the other words imply that someone talks too much. "Excessive" is used to describe something that is too much.
<u>Synonyms</u> are those words that share similar meanings to another. They can have either a <u>positive or negative connotation</u>.
The word <em>conversational</em> gives a <u>positive</u> connotation to a person that tends to chatter a lot. The remaining words (<em>blabby, gushing, </em>and <em>wordy</em>) give a negative connotation to this kind of person because they refer that this person is annoying due to his/her habit of "talking too much".