Depends on what you're after. The 400 speed allows easier use of filters, and people can shoot faster shutter speeds generally. However, there is more grain. That might be good or bad, depending on expectations. Delta 100 is very sharp and has low grain. I mostly shoot FP4 in 35mm because I am after a more retro look than the sharper Delta and TMax films. I only use prewar cameras though, and deliberately after a more vintage look.
Kent in SD