Kostyan, the growth is the same. And you described what I'm actually asking about: a bird with a leader or a random choice? For example, Pandora, from which you get a skill, and 2 skills to choose from. What do we take, stability or potential? I'll take the second one, even though I'll probably get into trouble.
Well, not exactly the same... Up to level 10, the Ranger has 35-45, and the Beastmaster has 30-50. Considering the higher percentage for earth/air - it's definitely Tazar. And also: there aren't many skills that are clearly worse than leadership that you can get at level 3, and their combined percentage is worth the risk.