Hamilton.
At the point of impact Max was substantially ahead and pulling forward at a decent rate as he had the line, so the rules clearly defer to him in that scenario without any qualification. In that regard its quite clear cut.
It almost looks like Hamilton was deliberately steering into him, but I don't think thats the case. I suspect he was understeering, on the wrong, dirty line, with a late entry and apex so inevitably heading for an early exit, and was working the wheel a little to try and compensate.
One irksome thing is the level of punishment. While I'm sure it was not deliverate, it was nevertheless a serious impact for Verstappen. Aside from losing the championship leader the opportunity to win any points he has written off a rival teams car. I doubt much will be salvageable from that, and at a time of budget caps thats a big issue for teams as it then compromises the budget they have left for in season development, something which Red Bull do a lot of.
That being the case, the penalty should reflect the effect it had on the innocent party. He should have been disqualified, the only punishment that is commensurate with the effects of the crime.
He got off pretty lightly, all things considered.