I would recommend Provide Support live chat plugin.
This live chat offers several option for adding a click-to-chat button to a website and different live chat window customization. All subscription packages have the same set of features and differ only by a number of operator profiles in the account. As for the chat agents, Provide Support offers operator console for all possible gadgets.
The prices are really reasonable and start from $8.25 for 1-operator package. There is free 10-day fully functional trial and 30-day money back guarantee.
As for the cons - Provide Support does not offer integration with CRM.
I can say that ProvideSupport Live Chat www.providesupport.com offers all the features available for all subscriptions. And you can try it for free for 10 days and decide whether this live chat software fits your needs or not. If there are some questions arise - live support is available 24/7, so you can contact them and ask questions in chat, via email or by phone.