There was a short-lived place in Manhattan called Zen Burger. They replicated McDonald's down to the heat lamped burgers and reconstituted fries except it was 100% vegetarian. Tasted pretty crummy but was really no better or worse than a typical fast food burger.
Just had one at Jardiniere (SF), it was perfectly decent, stunning only in its banality. A little softer, and a bit less chewy. Still good with all the usual toppings. Not as runny as I was told, but on the whole it was very easy to forget you're eating plant matter. I could eat it everyday.
I'm waiting for Impossible Burgers to take over.
https://impossiblefoods.com/burger/