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.

I'd say Honkai Star Rail is the most commute-friendly one, since it's based on turn-based battles. Genshin is definitely not the best one for that. Exploring the open world and doing quests take a long, long time. Honkai Impact 3rd has short missions too but it's action oriented.

I really think Genshin is awful on mobile. Even with a high end phone I had extremely bad performance. I haven't played Honkai so can't say anything about that.

To be fair I wouldn't recommend Genshin at all, I've been playing since launch and there's a lot of FOMO, so just by starting now you already missed many things that will never return (like weapons, events, etc).

I really liked the Nier Reincarnation game and played full f2p. The story telling and the soundtrack is beautiful. The game will be closing in the next months though, which is really sad. :(

I play Honkai: Star Rail daily during commute. The day mission can mostly be auto'ed. More complicated quests can be done when you have time.

Genshin Impact is my main game, I prefer the really polished open world combat, and down to earth stories with an amazing emphasis on being culturally accurate.

Also the game literally has no grind, so idk wtf the other user is saying. 95% of the content is done non-repeatable. Character's are time gated by an energy system, but there game is incredibly easy and it's nothing worth worrying about.