There are 2 things you need as President, firstly someone who will uphold the Constitution, be prepared to refer legislation to the Supreme Court and will, if needed, stand up to the Govt if what they are doing is breaking the Constitution.
The 2nd thing is that he/she needs to represent the country, "sell " us overseas and present a good image of Ireland and not embarras us.
None of the candidates so far impress me that they can possibly do both roles.
One name that does spring to mind is Olivia O'Leary.