Whatever subject interests you most! I have been told that History and Geography is quite heavy, and LC History differs greatly from JC History, so keep that in mind. You can rote learn your way to success with Geo and His. Art requires a lot of dedication but if you're a fairly artistic person and love art then go for it, although you have to learn about Art History as well :/
History and Art seems like a better choice if you're passionate about studying history since they're quite similar in relation to studying the past.It could be confusing having those two but they don't make as much of a difference.Unless you love art and you're willing to complete projects then history is no bother or other way around.With geography,there's more work and focus that needs to go on that subject.Not many people enjoy it since there's quite a lot more research you need to do and would have to finish a coursework paper.It's up to you to make the decision.This would be my choice if I were to choose a subject in Leaving Cert but I hope you'll choose wisely :)
If you're good at Art then choose it, It's a huge break in school being able to draw instead of writing. I find Geography easy enough too, and there is a project for the LC too so your result wont just be based on the exam. If you're good at History then I would choose Art, as 37.5% of the LC Art points are Art History.