Which do you prefer?
Aisling (Ash-ling) (means daydream, vision)
Niamh (Neeve) (means bright, radiant)
(I realise there are variant pronunciations of both, but those are the pronunciations we would be using.)
Niamh has just come out of the top 100, and was used 492 times in England and Wales in 2017.
Aisling ranks something like #1680 and was used only 18 times (this still surprises me!).
Are they both usable in England?