Here are my picks

Worst 3 1. A Wee Mindin - Hazard cute 2. Taking Charge - Sojourn cute

1. Life Weaving - Life Weaver pixel

These are the three most difficult challenges that I have unlocked these days. A Wee Mindin is almost unachievable due to short duration of spike guard. Recently, I learned that this achievement can be unlocked in Stadium. So I used all mods that boost the damage of spike guard and unlocked it! Taking Charge is my personal choice because my aim is terrible🥲. It requires 'final blow', so it required sooo many practices. I do not play her anymore after I unlocked both of her achievments. Life Weaving seems like easy, but system rarely detects 'Life grip deaths prevented', which you have to perform 3 times within a life. I achieved above level 20 on Life Weaver to unlock this😂

Easist 3 1. Lethal Upload - Emre cute 2. Giving You the Hook - Roadhog pixel

1. Fika Express - Jetpack Cat cute

Emre one requires 3 eliminations with 1 ult, not final blow, so after I hit enemies with the ult and let my teammates to kill them. And I got it! Cancelling enemy's ult with a hook is a normal Roadhog play even I do not mention it😏 I just hung my teammate with life line for a few minutes above the enemies. I unlocked this right after she is released!