Leo is a bit more popular now, but it’s always been relatively popular. It’s still my favorite on this list. If you want to make it more complex / less common, you could go with Leonard, Leonardo, Leonidas, or Leonid.*previously posted as summitseeker* --hike more / worry less--
No idea whether you like them, or they’d be too big a stretch, or they’d be allowed in Sweden, but Lancelot and Lennox (Shakespeare) contain the ingredients for “Leo”.