Obviously Naruto isn't the weakest SM user, Ironically he's the best!
If you count RSM then Naruto is far above any other SM user, if you just count regular SM then only Hashirama is better than him.
I don't get why people think Minato is the weakest user when he's a "Perfect Sage", the problem is that he can't maintain it for so long just like Naruto couldn't at the beginning due to lack of training.
It just like Kakashi said, SM isn't Minato's forte! He's a speedster, he doesn't need to sit there absorbing NE when he can end the fight under a sec!
His limited time of SM can be solved via merging with MA & Pa & then you has "Unlimited Perfect SM", but yeah he lacked practice so he didn't master SM that's why he said I'm not good at it but nevertheless he's a "Perfect Sage".