I use Front instead of Zendesk because even in very early beta it had gotten many of the little details of what we wanted in a customer support product right. E.g. emails look like they come from me, instead of looking like they come from a ticketing system. And they do a good job at basic workflows like assigning tickets, and having side conversations about tickets. Other features I like are their keyboard shortcuts, and canned responses (though I expect other products have those as well).
For context, the Zulip support team is roughly 1-3 people, depending on who you count.