Used to like tupperware, but if I left something in the fridge until it grew green stuff (it does happen sometimes) I would feel bad about throwing the plastic away. So just a few years ago when the Glad Ware come out, I began to use them.
They are great for microwave, dishwasher, and the freezer. I especially use them for small bits of leftover dinner and when I am freezing my special mushroom soup for winter.
I really like them for their freezing capacity. And they stack very nicely. I think that I can either wash them or throw them away and not feel guilty. And, I don't buy too many of them. I buy about one set every three months. So not too expensive.
You can find them every where now. (grocery stores, pharmacies, and Walmart). Also, they can be good for other things besides food. Because they stack well, you can use them for hobbies (beads, string, etc.)
So I like using them. This particular type, the lid pops on. But you can find some of them that screw on, which in my opinion is better.