As far as I know, the standalones seem to work better with SDK and tool detection (I guess IntelliJ has to try to figure out which plugins to activate)

Some projects with mixed languages (like a Ruby backend, HTML/JS webapp) I've had to kick IntelliJ a bit to get it to cooperate and find tests correctly

Someone else mentioned CLion, I think Rider also has features you can't get via plugin (maybe there is no .NET plugin..?)