I would say just don't start one, these gacha games are probably not the best to start with from the beginning with it's fomo gacha mechanics and at the same time they want the player to login every day.

But if i have to say something. I don't know Honkai Impact or the boy game. Between Genshin and Hokai Star Rail, i would say the second one is a better game, but at the same time they quite different. Genshin is an open world exploration action game and Honkai Star Rail is liniar and Turn based. All of these gacha games are extremly grindy.