Mórtas Gaelach
Bród Gaelach

which one is better for a tatoo
i want it to mean irish pride i am getting it with my family crest

Bród na nGael

is what I'd have. I choose "bród" over "mórtas" because I've never seen the word "mórtas" before, but I've seen "bród" plenty of times to me an arrogant, boastful pride. I choose "na nGael" over "Gaelach" because it's used in such a fashion in so many other places:

Cumann na nGael
Clan na nGael
Glór na nGael
Féile na nGael

Using the actual noun over the adjective conveys a much stronger association... i mo thuairimse!

Bród na nGael would translate most literally as "The Irishmans' Pride"