Isabel or Isabelle - Isabel or Isobel, but not faux-French Isabelle.Claire or Clare - Clare; English.Kathryn or Catherine - Catherine, Katharine but not downmarket Kathryn.Kay or Kaye - Kay. The -e is redundant.Aveline or Evelyn - Evelyn; neater and tidier and shortens to Eve rather than Ave.Sara or Sarah - Sarah; English and traditional and no issues with pronunciation.Marc or Mark - Mark; English.Luc or Luke - Luke; English.Jack or Jaques - Jack; English.Niahm or Neve - that would be Niamh, presumably? That's what I'd prefer, for authenticity.Shawn or Sean - Sean, for authenticity.Celine or Selene - neither. Selene if necessary for the lunar reference.Kristina or Christina - Christina; English.Alan or Allen - Alan! Neater, tidier, always a fn.