If you don't like spoilers, then don't read.

From the shipudden and manga, we know sakuke has gone of to train under orochimaru to seek more strength.
Naruto has perfected his jutsu, and can do the rasengan, after training under jiraiya.
Question now is, whos more powerful? Judging from what we can seen so far?

ok

Sasuke
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1. Has sharingan, and even stopped kyubbi with it.
2. Has learnt wicked stuff under orochimaru
3. Killed orochimaru
4. And has control over orochimarus snakes as seen in d last manga
5. Has control over the curse seal
6. Can do the chidori, and can channel it over his kusanagi sword
7. Not to mention his katon no jutsu fire element technique
8. He can potentially awaken the mageyoku sharingan

Naruto
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1. Has kyubbi
2. Has kyubbi
3. Has kyubbi
4. Has his new jutsu and the rasegnan, and he was able to brush kakuzu from Akatsuki
5 Can probably do jirayas frog jutsus and other things we havent seen yet
6. Has kage bushin no jutsu
7. Has wind element jutsu

well thats all i know, feel free to add or subtract.

We have already seen proof of sakukes "badness" with how he stopped jugo and zugetsu with his snakes in d last manga.

So if sakuke and naruto jam at this level and fight, no holds barred, who do you think would win? Also remember naruto can't use his new jutsu ever again, cus of d effect on his own body, same with kyubbi.

It's unfail to hit naruto when he's down
just u wait n' see he'll soon be up
but for now,
i 'd hate 2 but - yes sasuke would win
( though they'd both probably die - ha )

Sasuke will win any fight with Naruto until the very last fight which Naruto might win using 'that jutsu'.

What is that jutsu? It's the jutsu that caused Orochimaru to train Sasuke until Sasuke became stronger than him. It's the jutsu that prevented Kakazu from turning a head towards the real Naruto when he discovered the clone.