I used JIRA in very small teams but took great care to configure it sensibly (it took quite a bit of work, I'll give you that). Everyone was happy and even commented on how it made life a lot easier than github issues or whatever other tool they used before.

The biggest problem JIRA has is tons of legacy that nobody needs (like subtasks, a pain in the ass to work with).

Configure the tool properly and it's actually quite nice to use, especially in combination with Confluence for specs.