I bought a bunch of burgers and made a spreadsheet to graph their basic nutrition stats against each other:

The HuffPo article feels more like a fluff ad piece than a real discussion or informative piece. But my data above is just data.

For the most part, it doesn't matter compared to what you top it with, or what kind of bread you use.

Surely "least unhealthy"

I bought some vegan veggie burgers from my local Indian grocery store a few times and it was legit 11/10. I can't find anything even close as good at American stores.

does it really matter how healthy they are?

If I wanted a healthy veggie burger I'd make it from scratch - burgers are junk food, stop trying to make me eat healthy!