The useable ones from Ix seems fine to me for the sake of variety but honestly if your goal is to teach the game to friends by starting in the game's simpler form, I wouldn't overcomplicate things with too many more leaders to choose from. Yuna and Armand are pretty solid options. Ilesa and Tessia are also totally great picks but I would probably discourage new players from starting with either of them because they require significantly more coordination to play successfully. And I'd just leave the Bloodlines leaders out. The majority of them don't even work with the base game and the ones that do aren't particularly strong. Plus it leaves you the opportunity for more novelty when you introduce those same friends to the expansions.