[exceptione]

Interesting link! It shows its age though (22 years), as it makes the point that utf-16 is already the "most dominant processing format", but if that would be the deciding factor, then utf-8 would be today's recommendation, as utf-8 is the default for online data exchange and storage nowadays, all my software assumes utf-8 as the default as well. But I can't speak for people living and trading in places like S.Asia, like you.

If one develops for clients requiring a varying set of textual scripts, one could sidestep an ideological discussion and just make an educated guess about the ratio of utf-8 vs utf-16 penalties. That should not be complicated; sometimes utf-8 would require one more byte than utf-16 would, sometimes it's the other way around.