@Carmilla:
Neither Yasopp is good one, nor Franky's father to me.
I even understand why Ace hated Roger, though I don't consider him as bad one and I love his character. But as long as we don't know anything about Dragon's personality, I'm neutral about his character and hate him as a father.
I agree with you that Yasopp is bad father but that only apply to us, looking from this point of view, for them he's an awesome guy.
Franky's father is no a bad father since he was probably trying to protect he's son, he was already in Water 7, so he'll be reaching the New World in a couple of month and having your 11 or so years old kid on board is not a good thing when your going to fight Pirates in the New World, he could have gone back to pick him up but Franky was presumed to be dead for a long time.
Dragon did the right thing on no seeing Luffy since it will just bring trouble to Luffy and his homeland If the Marines find out about his family or where he's from, so it has been pretty clear that everything Dragon has done up until this point is being for the greater good.
I feel this like this is more of a personal opinion though.
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@RobZilla:
That's all very true, but we've seen a lot of bad things happen to a lot of good people in OP and they didn't react anywhere near as emotionally as Ace.
C'mon it was perfectly fine for Ace to be such a whiny boy