HELP! University College Dublin, Liverpool, Cardiff?!?

So i live in the north east of the US, and i am thinking about studying abroad for a semester in the UK or Ireland. I am so nervous to make the decision however! I am happy and comfortable here, but i want to see places and meet new people! I have to make the decision by this monday and i am freaking out!! My choices are between University College Dublin, University of Liverpool, and University of Cardiff?! Anyone know anything about any of these? Are any good? Bad? Advice? Info on the schools? Any help would be great.. thanks! =)