Calling it a one-shot over and over despite having no proof that it can one-shot people on Erza's level doesn't make it true.
Tartaros was literally a few days after GMG, don't pull that bullshit. The same Erza from GMG was superior to an amped Minerva. Nakagami one-shotted someone significantly weaker than Erza. That's it. It also defeated an already injured Ajeel, so no that instance was not a one-shot.
And btw, Meliodas has shown to reflect point blank magic sword strikes before:
https://imgur.com/a/tbxOb So even if I agreed that Nakagami would one-shot him, he or his clones could very easily turn it back on Erza and she'd one-shot herself.
King's spear is only made powerful because he controls it using his own magic, Disaster. Otherwise it is just stated to be harder than steel. Erza's swords are made powerful because she controls them with her magic. You're reaching so hard with this bs argument.
Chapter 314 Makarov calls Kagura's power overwhelming. I have no idea how you turned that into Makarov not following their fight. The "fastest" exchange in their fight was Erza shifting to her flight armor and making half a dozen slashes in an instant. That's less than nothing compared to this:
https://imgur.com/a/sMwiG so again, I'm not nerfing, you're just misremembering and wanking.
You say wingblade would even harm Meliodas despite having no feats. I call bullshit. And I like how you quote "fodder" as if Jerome isn't actually fodder.
I didn't forget shit, water isn't doing shit to Hellblaze since it can't be extinguished normally. It had to be Absolute Cancelled by Merlin when Hendrickson hit Arthur with it. Natsu's dragon slayer fire has never shown to be able to burn things that are immune to actual fire, nor has it shown the ability to negate Regenerationn. Nakagami isn't cutting through fire that's on Erza's own body unless she wants to lop her own body parts off.
"Gilthunder and Meliodas barely fought." Did you even read NNT? They had a multi-chapter fight. "Meliodas' "experience" didn't help against Gilthunder or Hendrickson" - Again, clearly you're either purposely lying or you don't remember NNT. Meliodas was holding off Hendrickson and Gilthunder 2v1, and then Vivian came in as well, yet Mel was STILL able to hold them all off well enough to free Margaret from the Chimera.
So to summarize my reasoning -
Meliodas has demonstrably better swordplay feats. He has far more experience. He has Hellblaze that Erza doesn't have a counter for. He can Full Counter all of her ranged attacks at at least double the power. He can make Lostvayne clones to mess with her while he closes in. Erza's Nakagami's only feats are defeating someone far weaker than she is, and defeating someone who was already very injured. Her wingblade has no feats other than destroying a featless fodder character.
My vote still goes to Meliodas.