Wow! Thank you for all the votes! I was not expecting this distribution! In a way, I think all the options to this poll are correct at some point or another.
I personally think Vader hates everything, including himself and especially Sidious. Except, he does also seem to enjoy a few things though: scaring people, killing them, tinkering with machinery, and unlocking secrets of the Force that the Jedi had kept from him.
I don't think he usually specifically enjoys killing younglings, but I do believe that he has some sort of twisted mentality that if he can't have his kid(thought it was just one), why should anyone else?
Even if Vader hates killing kids, that would just fuel his self-hate and strengthen his connection to the dark side of the Force, the only thing Sidious keeps him around for. Mostly, though, he does seem to just mow down anything he's commanded to, and anything that gets in his way of proving his worth to the Emperor, kids and all.
I feel it's also possible that years of such remorseless slaughter further twisted him inside to the point that Vader actually could have enjoyed taking the lives of terrified, innocent younglings in stark contrast to how he initially wept on Mustafar at what he had done.