Xavier is one of the only X names most people know and use, often as a middle name following Francis, as in Saint Francis Xavier, cofounder of the Jesuit order, who got his name from the Spanish-Basque village where he was born.
Today's parents are beginning to reassess Xavier, now just outside the Top 75--almost the highest its ever been ranked. It is popular in several counries, and is in the Top 10 in Quebec.
Xavier was chosen for their sons by Donnie Wahlberg and Tilda Swinton-- as well as the middle name of Larenz Tate's son Miles. Note that though that initial 'x' does have a distinct appeal, the correct pronunciation has it beginning with a 'z' sound.
Trivia note: the X-men comics introduced the creatif spelling Xzavier.