It would be good if Emacs supported the Enchant multi-back-end spelling engine wrapper, as this allows users to configure spelling preferences more flexibly than Emacs (in particular, to use different spell-checking engines for different languages), and the configuration works for programs other than Emacs.
It seems that it would be pretty trivial to add, since Emacs already works fine (since 2007) if you set ispell-program-name to /usr/bin/enchant.
Enchant supports UTF-8 (and only UTF-8) as an encoding, so for optimum functionality, I guess support would need to be added to ispell-encoding8-command (though since this is enchant's only mode of operation, it's unclear that anything needs to be done).
In a wider GNU context, the GNU aspell developer wrote a few years ago: "I believe Aspell future depends on making Enchant the
system spell checker."[1] Enchant itself seems to be stable, portable, and support a wide range of spelling checker engines, including all those that Emacs already supports; it would be great longer-term to be able to simplify ispell.el by requiring Enchant, and thereby being able to rely on its UTF-8 support and single set of simple options.