I mean, I'm partial to Pyrex, and I've been meal prepping for over five years now. The 3-cup containers (rectangular or round, like from a Pyrex variety pack, because I'm not going to not use a perfectly good container just because it doesn't match the others) are the perfect size for a meal for me. I also use mason jars for freezing portions of soup, and I have a few pint-sized Talenti gelato containers for stuff like overnight oats, or cottage cheese and cherry tomatoes.

When I started, I used white plastic takeout containers from the local sushi place, and finally switched to Pyrex because the plastic containers were cracking and warping, and I was tired of not being able to prep tomato-based foods unless I wanted a bunch of orange-stained containers.