UCD vs TCD Undergraduate medicine.

Hey there, TCD student here. I would say obviously they are all very decent and generally similar, they all give you the same qualification. However, I would say that a sizable minority of my class do regret choosing TCD over other colleges. This is down to one aspect, and that is organisation.
I know that as a prospective student looking in, this might seem trivial, but in reality the atrocious organisation and communication has a really detrimental effect on how many of us experience college. In a way, it brings the class together and all the years can joke about the frustration of being a student at a college where the students seem to be the lowest priority and deserve to be treated with contempt, but if I could go back in time, I would choose elsewhere. The course is hard enough, you don't need external factors making it harder.

The quality of education is good, the main campus is top notch, the societies are really great, the Trinity Biomedical Science building is modern and a hub of research. There are plenty of prestigious scholarships and prizes available. Many lecturers are really impressive. You get to have meaningful clinical experience early on (earlier than others, I think) and in many varied settings. Hospitals are very easy to access via public transport. Exam resits are still free.
This is a traditional subject-based manner of teaching where you may be studying X in pharmacology and Y in pathology. RCSI I know have a systems based education, learning pharmacology, anatomy and pathology of the cardiovascular system at one time, maybe other college do as well. Seems to make a lot of sense to me. No pre-med, but I have come to regret not doing one myself- college is not a race to the end. Almost impossible to do Erasmus, which is a year long, and for some bizarre reason you are placed into the corresponding french year above (i.e instead of going from 2nd year to TCD 3rd year, you go into Nantes 4th year..)
Ultimately, I have a bias against my college, maybe when I complete my studies I will have a different perspective. Teaching is probably the same across the board, so I'd say go for somewhere that has other factors drawing you, clubs and societies.
Also don't discount RCSI. I didn't even know I could apply there (my school and I still believed it was a private college). I've heard there's a bit of hand-holding (which is not necessarily a bad thing), and if you are looking for typical student life, it may not be as pervasive in such an international class, but the teaching facilities seem amazing, and RCSI seem to value their students, at least.
Hopes this helps, and good luck with getting in!