How do you measure “ease of use”?
To some it’s easiest to do drag & drop, when working from an ipad/tablet.
To others working in a grid/table form, it’s easier to select a new value in a drop down list.
to some it’s important to have easy handover between mulitple persons, for others it’s just a 1-person team.
To some it needs to integrate with developer tools and version control, to others it doesn’t matter.
Modern test management tools like MS TFS, Plutora, Panaya, TestRails etc are all easy to use. So there are other factors in place when selecting the defect management tool that best fit your context.