this manga has so much potential to be the greatest shounen like Naruto or One Piece, but the constant nakama bs destroy it. that's what I think from the beginning to halfway when reading this manga. until I read the chapter where Natsu didn't choose any of power up seeds, that's where it's go down to horrible path.
from my perspective, Natsu could have power up both Demon and Dragon, and have an otherworldly three way fight between him, Zeref, and Acnologia. turning him into both Demon yet Dragon form, I think that's awesome. too bad that's become a waste.
and what's about Alvarez empire? I didn't see them fleeing, when did they fly back to their continent?
also they waste so much about Erza and his mom's story, August past, even Ajeel and the other Spriggan 12. I see a lot more potential for them to be part of the story.
for all overall, I think 8 is enough. no more than that. even though it ended horribly, I still like it.