I say EZ-may, and I've never heard any other.
I suppose Es-mee is legit, though I don't really believe in "legit". I think pronouncing it the normal way is best, which as far as I know, is EZ-may in the English-speaking world.
I pronounce
Esme and
Esmee the same.
All the combos are nice, apart from Gem, which I don't get.
Esme Lovisa would get my vote.