Valencia is meh, at least to me. Marbella is ok if you want to be on the mainland. Ibiza, Mallorca and Menorca are some of the best diving the Med can offer if you can ignore/join all the partying tourists in the summer season. The marine reserves are pretty much my wet dream, incredible how quickly the sea there recovered from literal thousands of years of exploitation.
You don't mention water temps on this wet dream of yours, on mine I wear a think lycra suit, steel tank, no weight belt, full foot fins with toes exposed and no head cover, like last week's dive.
Honestly, it doesn't have to be a reserve worthy of Cousteau's documental, my current daily diving is average at best, reef is obviously struggling and marine life is such a small fraction of what it was when I moved here in the 80's. So the dives aren't worthy of a report, I see the disappointment the few times a visitor join us, because my local area isn't like the brochures, but is 45 minutes from my living room and we enjoy it greatly.
So now it is on my best interest to move to Spain, starting in Valencia is just convenient because I have cousins there for the last 50 years that I like. They will welcome me, including husband and an almost 30Kg floof. From there I think I have the complete Schengen area to get a place to live. I'm just hoping I find a reasonable place to end my days where I can dive when the seas are good, without much complication. Not sure if the target towns of every drunk guiri of europe would be that place.
With that said I appreciate every opinion, I get that my wish is quite specific and I may not find what I want, but I'll continue looking for it.