What is the best support chat / ticket system for customer website according to You?

In my case i used LiveZilla which was free, but it bothered me. One must have desktop software, no instant messaging support.

Now im using Zopim.com, example is at http://instantcpanelhosting.com (chat bubble on the bottom right)

Then i found following free or cheap live chat projects:
https://www.tawk.to/features/#shortcuts - free, extremelly pretty, no IM support
https://crisp.im/en/pricing/#details - free, unlimited chats, 2 agents
https://www.clickdesk.com/compare-plans - free, IM support, 30 chats in one month max.!, well developed & supported
https://www.olark.com/featurelist - free, 20 chats in a month, many IM clients
https://www.livezilla.net/premium/en/?action=preview - free, unlimited chats, one agent, NO IM support, windows client
http://p3chat.com/pricing - $5/mo., IM support
http://www.imsupporting.com/pricing/ - $5/mo., 5 chats per day
http://www.smartsupp.com/cs/cenik/ - free, IM support (xmpp,jabber)
http://www.livechatoo.com/cs/online-zakaznicka-podpora-cenik - free, no IM, limitted monthly visitors
http://www.powerim.cz/cz/cena/ - $3/mo, pretty look
http://www.uigo.cz/#main-tabs - $2/mo.