The answer is "it depends on your goal."
   If you are at a quick service restaurant, like Burger King, and you want to eat healthier, you might consider ordering a veggie burger.  Burger King is now offering a Morning Star Farms Veggie Burger as indicated in the coupon book I received in the mail today.
   I eat vegetarian burgers on a regular basis, so I knew that not all  burgers are the same. It was time to investigate.
   Using the Burger King full nutritional menu - which you can see here, I learned that the Veggie Burger is not always the best choice.  I specifically focused on calories, saturated fat, and sodium.  Out of curiosity, I checked the protein amount.  It is generally accepted that Americans do not lack protein, and that they get too much of the other three things.

Goal One: To go meatless.  100% achieved with the Veggie Burger.
Goal Two: To get lower saturated fat.  Most of the time.
Goal Three: To get the least sodium/salt.  About 1/2 the time.
Goal Four:  To get the least calories.  Not a guarantee!

I compared the Veggie Burger to the Whopper Jr, the Double Cheeseburger, and the Tender-grill Chicken Sandwich. (SFA stands for saturated fatty acids or saturated fat)

WhJR                   340 cals    5g    SFA     510mg sod    14g protein
DblCH                  370 cals    9g    SFA     720mg sod    22g protein
Chick(no mayo)   400 cals    2g    SFA    1260mg sod   31g protein
Veggie                  410 cals    2.5g SFA      960mg sod   21g protein

   In this case, the whopper jr looks the best for red meat eaters.  The chicken has the least grams of saturated fat but look at the sodium content!  Notice that I listed the chicken without mayo.  The calories go up significantly when you add mayo.  In fact, the nutrition menu lists a couple of sandwiches with and without the mayo and the differences are quite shocking. The Whopper goes from 630 calories down to 470 if you hold the mayo, the Double Whopper goes from 830 down to 670 and even the Veggie Burger drops 90 calories down to 320 if you hold the mayo. 

I would STRONGLY consider how much that mayo matters.  You could eat a whole apple instead of that dollop of mayo!

Another thing, most of the salads on the menu have at least 500 calories and as many as 7 to 10 grams of saturated fat.

I learned all this from the online menu.  The National Menu Labeling Law will not require this level of detail inside the store.
Though the information I provided today comes from Burger King, the offerings at similar quick service restaurants might be equally as complex.