Atom

remember window configuration (reopens always the same panels despite closing them)

remember code preferences (I use word wrap and i have to switch it on every document)

High start-up time

There should be a better user tips manual page to learn keyboard shortcuts

It would also be beneficial if mathematical and data analytic tools were added

it has quite high start-up timing when you open large projects to work on it

Sometimes, atom closed suddenly and do not open again

It still lacks better options with the previews even though there are already some by users adding plugins

It doesn't have self-correct features for lint errors, unlike IntelliJ

Some of Atom's default UX could be improved. Depending on your previous workspace, it can open with two panes and a welcome tab in each, requiring you to close lots of cruft on startup.

Atom's documentation and plugin marketplace could be a little more discoverable.

Sometimes things do not work as expected. Atom has improved a lot over the last couple of years, but it still could use some polish.

Atom needs plugins for quality-of-life improvements. This is not necessarily a bad thing, as it allows you to customize Atom to suit your needs.

It would be nice if Atom had some recommended starter packages that come with popular plugins for highlighting, soft-wrapping and so on.

There are some plugins that could be turned into core Atom features, like Linter and Beautify.