[loup-vaillant]

Let's list the pros and cons of each libraries (let's assume we trust all 3 libraries):

Monocypher vs TweetNaCl:

  Good:
    Monocypher uses more modern primitives (Blake2b, Chacha20)
    Monocypher provides password derivation
    Monocypher is a bit easier to use
    Monocypher is much faster
  Bad:
    Monocypher is twice as big
  Conclusion:
    Monocypher utterly outclasses TweetNaCl.

Monocypher vs Libsodium:

  Good:
    Monocypher is much smaller
    Monocypher is easier to deploy
    Monocypher is a bit easier to use
  Bad:
    Monocypher is a bit slower (except Argon2i, which is faster)
  Conclusion:
    If performance matters, use NaCl.  Otherwise, use Monocypher.

Nothing new, you say?

> By all means, write your own crypto but DON'T USE IT! And of course don't tell other people to use it either.

Get back to me in a couple years, we'll count the CEVs since version 1.0.