The answer is it's up to you. A .com is faster to register and be done here. As its a popular extension, many of the most common names will already have been taken, such as business.com or lunchtime.com etc A .com domain name will be found in a search engine just the same as a .ie or a .org etc
A .ie just means that it is an Irish Registered business. You can still use it abroad and people all over world will still be able to see it over the Internet. A .ie is more expense as there is more red tape in terms of who may register it as you must be able to prove you have a right to use it. So Dunnes Stores can get www.dunnesstores.ie as they have a registered company with the Companies office. at www.cro.ie/search/
I would recommend getting a .com as they are cheaper and easily remembered.