I like
Annie. It's actually quite a rare name in my area. I've only known two. I don't see it as childish, maybe because the
Annie I grew up with was very sporty and stoic.
I see
Annie as one of those sort of fin de siècle frontier lady names.
Annie,
Nellie,
Millie, that kind of thing. The names are technically pretty flimsy but the people behind them are adventurous and daring.