In general it is part makers choice. That said, I’ve found when mixing 2mm and .1 connectors in breadboard it can cause the other .1 connectors in bb to not align to the grid properly. I not exactly sure why, but experiments indicate grid alignment in breadboard isn’t simple. It doesn’t seem to be (as I initially thought) keyed to pin0. I tried a simple 4 pin part, then moved one pin at a time off the .1 grid. Moving any one pin doesn’t seem to misalign the rest but with mixed 2mm and .1 connectors alignment doesn’t work right either. So if you have both types you may want see what alignment looks like and pick what works best.
Peter