I'm one of the few people in the universe who acutally found Connor interesting. He annoyed me, but that's ok, I only dislike characters to whom I'm indifferent.
The misconception is that Connor was simply pissed at Angel, when it is actually more accurate to call him conflicted.
It's hardly surprising that he would appear to hate Angel, I mean he was raised that way. It's clear to see that Connor can see part of himself in Angel. I mean, I actually jump for joy when the fight vamps together, because both Angel and Holtz notice the connection between them.
Connor's issue is with his identity and his identity is down to his family and finding purpose through that. Yes, Connor is whiny, because he's needy, he needs a family but the problem is, if he embraces Angel, then he has to accept his adoptive father has fed him lies but if he doesn't, he'll never find the answers he's looking for.
Part of the problem wasn't even Angel or Connor's fault. They have been products of manipulation and while they are still responsible for their actions it's understandable that they would fall prey to loneliness, jealousy etc.
Now of course his interaction is going to focused on Angel, because family is the main issue with him. He's the father he's longs to embrace but has been raised to hate. He's source of his identity and insecurity. Spying on his 'family' and feeling drawn to saving the family in Slouching, prove that this is centre of Connor's world.
The hearbreaking moment is when Connor seems upset that Angel wouldn't want him at the hotel. If he simply hated Angel, why would he care? Also when he calls Angel 'dad' in Habeas Corpses. A part of him wants to embrace, the other part wants to be better than him and the other part wants to kill him. All of these feelings are strong in him and none of them are reconcilable.
Angel also has issues. He loves his son but he also doesn't want to repeat the sins of his own father. By being stand offish, he also, unconsciously does some damage. He also wants his son to embrace him, so he can feel better about himself (most likely because of how his father made him feel)
Ok in short, I think there was a lot more going on with him than, "he's pissy and he hates Angel" I could actually go on about it but I'll leave it there.