I will be crazy and choose bread. For many years, I tried to eat "low carb" so I didn't eat much bread/pasta/potato/rice. I learned to cook with other options: quinoa, barley, lentils, farro, chickpeas, oats, etc. They all mix-and-match well with various sauces, vegetables, and meat.
I didn't miss pasta or rice at all. They are just filler and I think lentils and chickpeas taste better than pasta and rice.
I missed potatoes a little because I love French fries. Also, dishes like mashed potatoes are traditional for meals like Thanksgiving dinner (and usually Christmas too), so there is a sentimental attachment there for me.
I really missed bread a lot. Sourdough bread is popular in my area, and nothing can replace it. And a well-made baguette is a work of art!