For my son, I wanted a name that would be hip and cool, but not overly so, and nothing common or easily shortened to a nickname (e.g., Thomas / Tom). I preferably wanted something that started with a "K" sound or ended with an "in" sound to form an alliteration with his last name or to have a sort of rhyming sound with his last name, which is Carlin. We settled on Griffin, and still love it after 11 years!
For my daughter, I had been dead set on Harper for years, since before my first pregnancy with my son, We only had the challenge of finding a middle name. I wanted something feminine to balance the gender neutrality of Harper, and we eventually settled on Olivia. I also like that Harper has sort of a rhyming effect with her Carlin surname. Olivia was super common at the time, but I still really liked it and it was my husband's favorite.
Later, I realized that we coincidentally named both of our children with surnames as their given names, which was definitely a trend during that time frame. Even doing my best to avoid being overly trendy, I still fell into a trend accidentally!