I generally bring salads, and that works pretty well. I'll roast a chicken or chicken breasts and cut up the meat and put that on top, since it doesn't need to be heated. I usually make a week's worth of meat at once - which is 3-4 meals for me.
I've also roasted vegetables and brought those to work, which worked pretty well. Had one container with meat of some kind and the other container with vegetables.
Spaghetti sauce over vegetables & meat works nice. I also don't mind salsa over vegetables & meat. Biggest downside to spaghetti sauce & salsa is the sodium in it.
depending on how much you like to cook, you could find some indian curries - they are generally better the following day. I've made this before:
But, don't use potatoes. I added some carrots and it worked out pretty well.