Like somewhat more popular twin sister Reagan, this vibrant last-name-first Irish choice makes a strong, straightforward option.
She does have a couple of downsides though. Regan entered the girls' list in 1974--one year after the horror flick The Exorcist featured the demonically possessed Regan MacNeill. And before that, Regan was one of the faithless daughters in Shakespeare's King Lear.
But putting all that aside--and you can--Regan makes a worthy successor to the overused Welsh Megan.