I think he went with microATX because of possible size constraints.
Midtower are somewhat easier to build and modify simply because they are larger.
In scanning his specs, his very high and high were the same board and processor for the two categories, thus will have similar performance.
The ITX machines are even smaller but will take a bit of a performance hit.
All appear to be nice machines. Depends on how much you want to spend. Easier if it is gov'ment money, or if you are independently wealthy (yeah, right.)
