I have a set of pyrex bowls that I bought in 1987, and still use today. I wouldn't bother with wide mouth jars, although I guess they have advantages when storing food in the fridge.
But for food heating I find it very easy to just take the food from whatever container it’s in and put it in a regular bowl which I can microwave covered by a plate to contain the inevitable food explosion.
Every one of the few times I microwaved even in high quality plastic containers they became soft and harder to handle. Also I always had the (probably very subjective) feeling that it subtly changes the taste of the food. Kind of how bottled water tastes when the PET bottle is left in the sun for a while.
Anyway, I find the bowl+plate as an infinitely reusable option, easy to clean, and just takes a bit of extra care handling when hot. Also bowls and plates stack very nicely in the cupboard and not too expensive in IKEA.
The default (maximum) power setting dumps so much energy so fast into the water in your food that some of it boils, and the expanding steam spatters food everywhere. This is also what causes the "burned on the outside, still cold in the middle" effect with leftovers, which aren't engineered to be microwaved on high the way most frozen packaged meals are.
Use a lower power setting for longer, and pause to stir if possible. That way there's more time for the heat to dissipate into the bulk of whatever you're microwaving, and few to no tiny, messy steam explosions.
I discovered this accidentally since usually I go about other stuff while heating the food in the microwave (not the stove) and more often than not I completely forget about it even with the “ding”. Putting it though another session at low power, I noticed, makes the food very uniformly heated.
But ever so often after a while heating there’ll be the random drop of water under some fat or something like that, and without a lid it will paint the inside of the oven a lovely shade of splatter. No downside with covering the food.