Of those listed, I like Subway the best, but I might eat McD's more often, only because I'm most likely to eat fast food in the car, and a burger is easier to eat while riding/driving than a sub. And they have the dollar menu.
Don't eat Subway anymore- those meats sit out too long, I dunno. I got food poisoning from there last year. Other than that try not to eat the stuff. It's SO bad for you. If I have to I eat Carls Jr chicken sandwich which is a REAL chicken breast on a wheat bun, no sauce.
For me Wendy's tastes to wierd, i've never eaten at Subways ever in my life, only eat the ice-cream things and breakfast stuff from McDonalds, and I guess burger king is ok. But although it isn't up there, I like DQ the absolute best. I love DQ!