Yeah i would pick TCD i mean i didn't apply to these schools so take my opinion with a big grain of salt but i've read on this forum before that one person has been dissatisfied with RCSI's facilities including its teaching hospitals.
To repeat chronos's point TCD is ranked somewhere like 45th in the World as a university, its the oldest in Ireland and cheaper. It will likely have more name recognition because its a university with many subjects.
Quality and student satisfaction i honestly don't know. Are there Irish university rankings that take into account student satisfaction?