I prefer
Amabel by miles. It's such a tender sounding name, kind of dusky pink, makes me think of roses. It's classic and really underused.
Annabel just sounds kind of stiff and awkward, with none of
Amabel's warmth (although I do love
Anabela - it's the only
Annabel variant that looks balanced).
Pronouncing
Amabel like amaybel never occured to me - I think people would get used to
Amabel quickly since the pronounciation is fairly intuitive. And I imagine spelling would be easier to deal with than
Annabel since there are fewer variants.
Amabel and
Annabel do look very similar in some people's handwriting though. It's not enough to put me off the name but it could be annoying.