Hey Kristoffer Rønn-Andersen thanks for the feedback! Oxford University researchers actually published a study along these lines in 2018, looking at the varying impact across different producers in terms of production, transport, and packaging. Essentially they conclude that any plant-based protein or non-dairy milk will always be lower impact than the lowest impact meat and dairy products, but beyond that there are huge differences amongst meat/dairy producers — so definitely a good place to start for meat-eaters is avoiding the very high impact producers.

There’s more info on the study here: http://www.ox.ac.uk/news/2018-06-01-new-estimates-environmental-cost-food