Moreover, I saw a game by Alex where, at the beginning of the game between Moandar (with advanced training from the start) and Moner, he chose Moner.

Well, if Alex himself chose it, there's no argument. It's Alex himself. There's no need to comment further.

In that situation, it's obvious that Moner is the better choice because the game is fast-paced, he has logistics and attack, good penetration, and a good movement range. (And Moner himself levels up in attack more). And the hero will gain experience anyway.
(And if you're playing on the Conflux map and have a bonus for psions, and considering that they can be upgraded and tear everything apart).

But yes.

Normal percentage.

forgetting about him when the hero reaches level 21 is even "more normal".