Aang had his issues and being so focused on his work as the Avatar that he didn't spend time with his kids is realistic. Plus, before Tenzin was born, Aang was the last air bender. It's not hard to believe that he'd be overjoyed to have a son who was an air bender and be bias towards him.
Well I already said I understand that he would be a distant father, and I said that I get that he would have bias toward Tenzin, I’m not against that. I just personally don’t see Aang allowing himself to extend it to a level where he makes his other two children feel worthless, I mean, how much more effort could it take to load 3 more people on appa and vacation as a family, since he clearly found time to vacation “many” times with Tenzin? It just doesn’t sit right with me.