This one does what it's supposed to do. It connects your site with the onWebChat service, and it does it very well so far.
Ease of use
Not much to say here, as just add your ID. The real work is done in the onWebChat's administrator panel (very clear and easy to use)
Very fast responce,at least when using their live chat (of course they use their own service :-)) I guess they won't be awake 24/7 though...