Fretless is wonderful. It is great very a variety of music, but sounds particularly good jazz, acoustic folk, classical, different types of rock, country... So the first consideration when deciding whether to go fretless is the style of music you want to play. For instance, fretless is probably not the best for metal or funk. That being said, perhaps fretted basses are more versatile. For me, I just don't like any buzzing on the strings as they hit the frets.