* -ship: Speakership (this is less common and usually refers to the role or position of a speaker, like the speaker of a house of parliament)
* -er: Speaker is already a noun formed with the suffix "-er" indicating someone who performs an action.
* -ing: Speaking (this is a gerund, a verb form used as a noun)
* -y: Speakery (this is informal and may mean a place for speakers or a style of speaking)
You could also use prefixes like pre-speaker or co-speaker.
Ultimately, the best suffix depends on the specific meaning you want to convey.