When I think of "pretty" for boys names , I tend to think of more traditionally feminine ending name sounds eg "ah" - so Noah, Ezra, Asa, Micah, Jonah, Luca, Elijah etc or "ee" ending sounds - Louie, Rory, Jamie, Harry, Charlie, Toby, Finley etc.
Or you could go for romantic/poetic sounding names imo - Emrys, River, Gabriel, Maxim, Tristan, Heath, Laith, Rowan, Sebastian, Xavier, Leander, Caspian etc