If you're looking for live chat tools to add to your website, then I'd recommend checking out market leaders like Comm100 and LivePerson.
Neither are the cheapest live chat customer service tools, but they are the most well-known for a reason.
But, if I'm honest, my suggestion would be to seriously examine whether you need a live chat option in the first place!
If your website is so hard to navigate and purchase products from that you need someone to guide customers though, you might be better off speaking to a UX designer about improving the usability of your site.
If you fell like having live chat on your site will improve engagement or sales, I'd also suggest finding a way to run a controlled test before you purchase any of these products.
I'm actually reading a book at the moment about the mistakes that various tech companies have made in the past, and there was a brief mention about how live chat on site didn't always improve business.
So the take away lesson here is test out your theories in a cost effective way first, and be wary that live chat customer service on a website does not work for everybody.