18650 pack building - is it better to have similar batch or similar capacity?
There are lots of videos on YouTube that answer the question. They cover all sizes from small to automotive. One particularly prolific and experienced builder is jehugarcia He has done at least one video where he measured a whole batch of cells and picked the ones that nearest matched capacity. Also look at Instructables there may be more information there.

The problem is that if the cells don't match in capacity then you run the risk of overcharging the weakest and similarly reverse charging the weakest when you run the battery near flat. A good BMS will alleviate most of these problems, but applying it to 100 cella is probably too complicated.