I don't know much about Aviomar - besides being a RYR partner - but I've heard really good things about AFTA overall. They seem to have a large, modern fleet; in-house maintenance (I think); flying from a commercial airport; great instructors and training; varied weather for tricky IFR flying. As always, get yourself a class 1 medical first and visit your shortlisted schools in person, but AFTA seems like it's in a good position at the moment.
I visited a pilot careers fair where I got to speak to AFTA. I explained my fears of integrated schools collapsing during training. They said that due to another ATO having folded and leaving students in a sticky situation previously, the Irish Aviation Authority has since ensured that Irish schools have regular financial checks (every year i think?) to ensure that the school can actually deliver to its paying customers/students. Obviously, keep in mind that this is what was said by them as a recruitment/marketing team; however I'm sure you could contact the Irish Aviation Authority to confirm all this with paper trails and check that AFTA is financially stable.