I don't really like either as they both sound like old lady named but you know what, several conversations I've had fairly recently with 17-25yr olds (I'm 42 but work in an industry alongside a lot of youngsters) have made me realise what We consider old and and dated does not even occur to them to think of as such - they are so far down the line it is all Jesu knew to them iyswim? Like fashion, music, film, books - all the 'oldies' or classics to their generation are just unknowns (I've had some quite surreal conversations!)! So for your daughter's generation it will be even more so - Especially as to be perfectly Frank all the Original old lady Mabels and Sisters will Definitely be dead by the time they are of an age where their peers are consciously 'noticing' each others names.
What I'm trying to say is ignore the 'that's old fashioned" brigade and choose whichever goes best? Although as an afterthought, as someone who Always shortened people's names as a child think about the abbreviation sounds too!