Again,
I don't know much about Ireland, as I only visited UK schools in January for my interviews (Hull-York, Nottingham and Birmingham), but I can tell you that those 3 schools facilities are far superior to the meds facilities here in Kingston, Canada where I am studying my BScH in Life Sciences (Queen's University).
My point is, UK schools match up to Canadian meds. Even on rankings, schools like Nottingham/Birmingham are in the top 100 in the world, with the London schools cracking top 20 results.....only 3 Canadian schools crack top 100 (UBC, Univ. of TO and McGill), but with that said, Trinity is also top 50, so Trinity is definitly world class from what I've read and heard.
So it boils down to what you would prefer on a personal level (ie. facilities, reputation of program, city life, etc.).
I guess I picked Birmingham because:
1. Its a huge city, over 2.5 million people, big nightlife
2. Campus is awesome, Facilities are great, large class size which I prefer
3. I get to live in a big city for a low cost of living (much cheaper than London)
4. Its only a 90 min train ride to London
5. It has an international airport, so I can fly direct to Toronto and avoid the London nonsense. Also can travel anyhwere in Europe quite easily.
So as you can see from my reasons, its nothing to do with UK vs. Ireland, its more to do with what you'd prefer personally.