..... I have been lucky.
Malta is probably my favourite place so far, though the water wasn't as warm as the Red Sea and there wasn't the colours/quantity of coral and fish, there is a lot of decent wrecks and Geologically interesting dives, and just about all can be reached from the shore. Its cheap and they even drive on the left (at least officially). Its kind of a warmer more compact version of the Northern European Archipelago (that may be slightly to PC) with better vis from what I can tell.
Crete was where I learned to dive, but I didn't get the impression there was as much interesting diving as the other locations. I guess if I was going on a diving holiday I would go somewhere else, but if I was going there on holiday anyway I would enjoy the diving.
I am still very much a newby, so weight my opinions accordingly (i.e. have a pinch of salt handy).
As for Ireland, I used to spend my summers off the south coast, sailing, fishing etc., so I would really love a chance to sea below the surface.