The one whom speaks the loudest

Sometimes in a social gatherings or even in a formal office environment...you often come across people whom are loud.
Not only loud but annoying...they would always want their views heard and also agreed upon.
A critical view is something they're not wanting to hear.
How do you deal with this situation. Fight back and make your voice heard.
Or keep quite and just nod away in frustration....
Hmmm....I'd rather take the third choice....ignore and walk away politely:-)
What would you do:-)