I like the Ali Baba Magic Food truck at the 37th street food truck court ... the falafel is standard, but the tabouli is nice. Tastes very fresh. The chicken sandwiches are good too. In that same area the crepe sandwich truck is decent. They could have more flavor.
I want to try the truck with jerk chicken and pork at the post office near 30th street. It's on market street. I went once but there was no server to be found.