Bachelor member of Tuperware Team checking in -- namely those red, snap-together Easy Find lids. I've purchased 2-3 "sets" of those plus extra 2c boxes, and right now I have 4 bowls (2c) and 2 mugs (1.25c) of frozen soup in my freezer.
I don't like the idea of disposable plastic either, but so long as the boxes don't get a gravity assist, they're fine. I've lost two in the last five years, and they get regular workouts from freezer storage to daily lunchbox organization.
I will use ziplocks when freezing meat. I use plastic grocery veggie bags, but I make a point to stuff them in my grocery pack and reuse them several times. I'm nowhere near the 173 reuses of a cloth bag for the material breakeven, but I'm nontrivially closer.
I've used Pyrex before. It's heavy, chip/break prone, and sometimes grows legs from the office fridge. It's really the weight that concerns me, oddly.
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As for _heating_ leftovers, if you use a microwave, look into a plastic or ceramic plate cover. Reduces splatters, reusable, dishwashable. A former roommate had one, and it was on the short must-have list when I moved out.
A close second is the frying pan. If I'm not heating something obvious like soup, sometimes I'll chop everything fine and run it through a stir fry, maybe with something new and fresh to keep the dish interesting.