When I first started, I relied on packaged foods (mainly Lean Cuisine) just to get the diet kick-started. Then, after I saw some success, I started to cook my own meals. I still do eat the occasional frozen meal (like tonight!) but have found that I prefer cooking when I have the time because then I can control the flavor and portion size.
Have you tried the Kashi chicken enchilada? I'm not a fan of the Kashi cereals and some of the granola bars are very bland, but I have been pleasantly surprised by the flavor of their frozen meals. I actually really like the chicken enchilada entree, the whole grain pilaf is pretty good, and there's a lot of fiber. I haven't tried Medifast, but I found Nutri-System to be unbearable.
Another possible option, if you do have some free time to cook once per week, is to make a big batch of something that you can portion out and freeze. You could cook six chicken breasts, some brown rice or whole grain, and maybe some veggies, put it all into six individual serving dishes, and refrigerate/freeze them. Then you have a full week of dinners. Or if you want fresh veggies, you cook the veggies fresh and add a salad.
Good luck. My cousin does well on Medifast when she manages to stay on a weight loss program.