I don't know if these are the least calories but they are the ones I like best. My favorite and only one I eat from Healthy Choice is Chicken Margerita(FABULOUS!) It sounds like it would be Mexican inspired but it is actually inspired my Margerita pizza. The "spa" choices from lean cuisine are the ones I eat because they say they use whole wheat pasta and they have lots of veggies. I like the lemongrass chicken, sesame chicken, butternut squash ravioli (don't usually like vegetarian stuff but this one is good. You can always put 3oz of lean protein with it for only about 100 calorie), garlic ginger chicken.
I have only been doing SP for a few months now so I'm no expert but one thing I have tried to over come is always go for the thing that has the least fat, carbs, calories, etc. As long as you track it and it is within your range you can have it!!!
Also, I don't know if you have a Trader Joes near you or not but they have tons of things that are already prepared or quick to fix to chose from. If you need any recommendations from there let me know!