Email channels and pre-ticket forms are dealbreakers for being a Zendesk replacement. I can live without a lot of ZD's features (and be happier for it) but those two are table stakes for me. I could see this being a replacement for Intercom, but Intercom isn't a fit for us either.
The stuff ZD and Intercom (and SFDC) are awful at, where there are opportunities for something else to swoop in: even partial Markdown support for incoming messages, integrations with third-party docs/KB sources, live queue dashboards/visualizations, toggling features based on different support plans, and facilitating handoffs for follow-the-sun support (multiple queues, defined regions/hours per queue, auto-reassigning active tickets across agents and queues, cleaner or richer ticket summarization options).
Yeah agreed, KB integration was another big one, as well as shortcuts when you have agents who do 3-4 chats at the same time. In fact the ability to define agent capacity individually and by role to begin with is important.
The ability to define different capacities for the same agent across different queues and how to aggregate that is also an advanced feature which is useful. E.g. I can take 3 in English or one in French and one in English. Or I can take 4 tier one tickets or 2 tier two tickets. Or I can do x tickets for customers on basic support but if I'm on with a customer who has priority... Etc
Queueing and assignment logic gets tricky because requirements can be vastly different across organisations. Hence why there are companies at the high end charging enterprise money.
The stuff ZD and Intercom (and SFDC) are awful at, where there are opportunities for something else to swoop in: even partial Markdown support for incoming messages, integrations with third-party docs/KB sources, live queue dashboards/visualizations, toggling features based on different support plans, and facilitating handoffs for follow-the-sun support (multiple queues, defined regions/hours per queue, auto-reassigning active tickets across agents and queues, cleaner or richer ticket summarization options).