I don't see how you can say that they aren't equal in skill. Goku purposely guaged his power so that they would have a fight on equal grounds, and they stalemated. Neither could get the upper hand, so that means they had to be equal in skill. Also, Goku was fully committed to the fight, but when he saw that it wasn't going anywhere, that's when he tried to convince Vegeta to give it up. After Vegeta killed those people, you can't say Goku wasn't fully in that fight. He was going at it full force.
As far as your comments about Vegeta winning when he's stronger than his opponent and losing when he's weaker, that same thing can be said about any character in DBZ. That's how all the fights went. Same thing with Goku. The difference between him and Vegeta is that when he was outclassed, he either had a trump card or help. Against Vegeta early, he had Kaioken and then Krillin and Gohan's help. Against the Ginyu force, he was just flat out stronger than them. Against Freiza he was getting his ass whipped until Piccolo stepped in and gave him the chance to use the Spirit Bomb and then he went SSJ and was flat out stronger than Freiza. The second Vegeta vs Goku fight was one of the rare instances in the series where two people fought on equal ground, and once again neither of them could get the better of the other.