Sasuke's External Powerups:
-Curse Mark: Lost forever.
-Orochimaru Abilities: Lost forever.
-EMS: No proven benefit other than restored eyesight.
-Rinnegan: Unmastered, with a single ability unlike any he has had previously, and a learning curve.
Sasuke's Inherent Powerups:
-Increased Chakra Potency: Uchiha trait.
-3T Sharingan: A given. He was born with it.
-Precognition*: Allows him to see briefly the moves that will come.
-Jutsu Recreation: Only used to copy Lee's speed so far.
-Genjutsu abilities*: Require training.
-MS: Fought for and earned through hardship in battle. Lost forever, replaced by EMS, which is for all intents and purposes, the exact same thing.
Naruto's External Powerups:
-The Kyuubi: So many benefits that they need to be listed as separate abilities (but don't worry, I'm counting them as one, just to give you every single handicap you can get, to prove my point even further):
-A: 1000x chakra of the average Chuunin-Jounin Level Shinobi.
-B*: 1000 years of knowledge used in a multitude of battles. (For fun, let's not even include this benefit)
-B: The Greatest healing factor in the manga, only possibly outclassed by Hashirama's Senjutsu or the Yin Seal.
-C: Complete autonomous control. He can literally take over and fight Naruto's battles for him, body and mind.
-D: The ability to gather massive amounts of senjutsu with the greatest speed and control we've seen in the entirety of the manga.
-E: Chakra potent enough to boost the power of any ability used.
-F: Enhanced physical abilities, to the point that Naruto became faster than Ay without a day's training.
-Red Blood Chakra Cloak: Vast offensive and defensive abilities. Lost, but apparently not forever* (But let's give you the handicap and count it as Lost forever).
-Kyuubi Cloak Mode: Only partially earned, as he was given support by Bee and Kushina, and had Yamato as a fail-safe.
-Bijuu Mode: Increased Speed, Power, Reflexes, and Jutsu strength because of friendship. A handout. (But for fun, let's not even count it.)
-Bijuu Sage Mode: The ability to combine Bijuu Mode with Sage Mode, increasing the power of both. Not a handout, really, just super convenient. (But for fun, let's not even count it.)
-Ichibi: All abilities by request.
-Nibi: All abilities by request.
Sanbi: All abilities by request.
Yonbi: All abilities by request.
Gobi: All abilities by request.
Rokubi: All abilities by request.
Shichibi: All abilities by request.
Hachibi: All abilities by request.
Six Paths Senjutsu: Innate comprehension of the inner workings of all jutsus. Flight. Increased durability. Increased reflexes. Increased Sensory abilities. Gudoudamas. External regeneration. No training required.
Naruto's Inherent Powerups:
-Increased Vitality/Chakra: Uzumaki trait.
So if my estimates are correct, it seems Sasuke's 4 external handouts edge out Naruto's 11 (Which is really around 17 total, but we're giving you people the biggest handicap here) or Sasuke's 7 (more like 10) total "handouts" also edge out Naruto's 12 (more like 18).
So math's not exactly on your side. But let's count how many Sasuke has at the end of the manga compared to Naruto. Looks like Sasuke lost 2 of his handouts. Seems to put Sasuke at around 4 or 5 (8) compared to the 1 Naruto lost throughout the manga, still leaving him with 10 (17) or 11. Huh.
But wait, with all of those powerups, Naruto must have had to juggle a lot of different abilities and master many different fighting styles, right?
Wrong.
-SM: Physical boost. Bigger Rasengans.
-KCM: Physical boost. Bigger Rasengans.
-BM: Physical boost. Bigger Rasengans.
-BSM: Physical boost. Bigger Rasengans.
-Bijuu Abilities: Physical boost. Bigger Rasengans. All work done by the Bijuu upon request.
-6PSM: Physical boost. Bigger Rasengans. Inherent abilities requiring no training or consciousness.
Whereas Sasuke's abilities...:
-Sharingan: Manipulating Eye Power.
-Curse Mark: Manipulating Bodily Power. Physical Boost.
-Orochimaru's Abilities: Entirely new jutsus. Physical Boost.
-MS: Manipulating Eye Power. Entirely new jutsus.
-EMS: Pretty useless.
-Rinnegan: Manipulating Eye Power. Entirely new jutsus.
And that's not even mentioning the adjustments he would have had to make after switching around his fighting style so many times after each loss or acquisition of power, and fails to get into the fact that Naruto's abilities are vastly superior (every powerup he has acquired has given him offensive and defensive boosts passively, sensory abilities, and a chakra boost, while Sasuke's actually drain his chakra faster and require acrive use), giving each of his acquired abilities more weight than Sasuke's, but again, we're giving you a handicap here just to prove how ridiculous this argument of yours is.