I'm using Jira, not a huge fan (mostly because it's slow, the cloud version at least) and there's some clunkyness BUT every time I looked for alternatives it was either too opiniated (like SCRUM or nothing) or had really poor integration with dev tools. The big advantage of Jira is that you can customise it quite a bit and it has a good set of integrations and APIs.

I'm still thinking of moving away at some point but haven't found any alternative...