I've played dota 2, league, and valorant for at least 1k hours each game. League is way harder than valorant mechanically and strategically since you need to account on different things at the same time like positioning, laning, map awareness, different abilities that being thrown at you, landing skillshots, etc. But dota 2 is way harder than league, its basically league on steroids where you have more abilities, longer game, denying of creeps in laning, animation cancelling, more active items that's a double edge sword etc. The only thing where league is harder is on skillshots. The thing about valorant is that if you can shoot heads you can climb at least ascendant on rank, just pick iso, jett, and reyna and you can easily destroy enemies if you just have great aim.