While I do agree that Angel has a bad habit of making unilateral decisions, I don't think the two exmaples you've listed are comparable to what Wesley did in Season 3. In IWRY, Angel makes a decision about his own body and his own destiny and the only negative effect is that he can't be with Buffy. No one else is affected, no other lives are altered. When he agreed to W&H giving Connor a new life, he was literally saving his son's life and ended up making said life better. I don't agree with him allowing W&H to alter his friends' memories without their consent, that was a huge violation but, again, no one's life was really altered or affected for the worse.Honestly, my biggest issue with Angel as a character is when he thinks he knows better than everyone else and thus makes decisions for them, like with Buffy in I Will Remember You or the whole gang, at the end of S4. Their opinions deserve to be considered, and he doesn't even question for a moment (or seems to at least) whether someone else's opinion might be as or more valid than his own. I don't know if it's his age or his position as the leader in LA or something else that makes him think he knows better, but I'm irritated by the lack of consequences he's dealt when someone like Wesley doing the same thing gets punished by having his throat slit and all his friends abandon him.
Meanwhile, Wesley made a decision to hide a prophecy from his entire team out of pure hubris. He met with Angel's enemy in secret. He betrayed Angel and Connor by kidnapping Connor, leading directly to Holtz kidnapping Connor, tearing Connor away from his father and putting Angel through the torment of losing his son. He was at least partially responsible for Connor's traumatic upbringing in a Hell demension. And he never apologises or admits fault. His actions ruined Connor's life, caused Connor and Angel irreparable pain and trauma and altered that relationship forever. So yeah, not really on the same page as what Angel did.