I'm usually ok with what macOS Character Viewer offers.
I am rarely on Windows and didn't know about BabelMap. It looks like it fills the gap there.
I work mostly on Linux so I hacked a Character Viewer clone in Rust over a weekend recently[1].
It just does what I need but I'm planning to add features to it if I find them useful.
So I am curious: what functions does BabelMap offer that you can't live without, especially as a typographer?