When it is possible to choose a breed, feel free to do so. It is a late grief to fight a race we can play less. Several smaller ships will produce the desired result, instead of just building one big ship. Ground protection is only worth avoiding in two cases.
It is that the spies of the other empire are much stronger than ours, and we could not recapture a fortified planet packed with forts. There is also a situation where our superiority in space is so reassuring that it would be detrimental to spend on ground defense. If you want to guarantee reliable antispyware as a priority, unfortunately there isn’t that much money left for infiltrating spies. This is when spies fail multiple missions.