I'm not debating on anything, I'm stating something since people above me started talking about this again. Oh well, I'll pitch in some more.
I said rasengan is more powerful than chidori, power-wise. Rasengan is also a killing technique, invented by either Jiraiya or the 4th. I'm pretty sure it wasn't designed to cut down trees, it was invented as an all-powerful technique used to kill the enemy ninjas with 1 strike, just like Chidori. Unlike chidori, it's based solely on chakra manipulation, and due to the nature of the technique it looks a lot less threatening than chidori (chidori looks REALLY powerful).
I agree on one thing though. Naruto will most likely use a much weaker version of rasengan against Sasuke because a fullpower rasengan (the one against Kabuto) would kill Sasuke instantly. I don't think Sasuke can control the power of chidori even if he wanted to hold back, due to the nature of the technique.