Okay, based on my full experience and knowledge in speedrunning this game over 50 attempts and hundreds of hours, I will say that Dodonga is the most challenging one in the entire category dyue to the fact that it has the most competitors and most runs in one category.

The current world record is pretty optimized for 3 phases Dodonga but if someone managed to do the 2 phases dodonga kill then it might be an impossible time to beat again and I can't wait to achieve that moment.