Thats a tricky one, you can read on the net everything about it but for Irish Terriers i want to add something to all this :
An Irish Terrier dog is a real macho, full of himselve, no fear whatsoever, you can make him happy but never can make him afraid. They are much tuffer than a bitch. We lived a year in South East London and he met many pitbull kind terriers but they never ever try to fight him, Irish terrier dogs have an extra ordinary attitude over them wich you can't compare with no other dog breed, thats why there nicknamesare "daredevils"
Sleeping at night in the garden, rain, storm, cold, snow it doesn't matter he is on guard.
An Irish Terrier bitch is also fearless but much easier to handle submissive in a good way, and always happy to please you. They are sharper as a guard than a dog but they are also much more barky.
If you have to make the choice listen to your heart.