It's a bit of a question and like you say depends on the writer (and the scene in question, really)
Most of the time she just seems to toss people about with it, but then you have her holding up that large control tower in Civil War. Or, exponentially more impressive, tearing through straight up Vibranium to rip out Ultron's "heart".
And if she could lift Hulk, what good would his strength do him? It's not like there are restraints or anything he could break, so the only thing to really limit what Wanda could do is his weight.
I always did think the best/easiest way one could kill the Hulk would be to get a strong enough telekinetic and simply lift him into space with a nudge toward the sun maybe. Then he'd either suffocate or be incinerated.