At the moment, I have 6 fretless basses (34 inches scale), all unlined and 5 of them are sixers, the sixth one being a 4 string.
My third ever bass way back in 1987 was a fretless (a defretted Aria Diamond 500/1 copy painted in pearly yellow with two EMG HB pickups and a piezzo under the floating bridge) as I always wanted to play fretless and since then almost did with very few incursions in the fretted world.
I prefer unlined fretless basses, but really don't care if they are lined with frets positions at the fretted place or at the frets places as I only look at them when I'm some kind of lost after a huge slide or a technical acrobatic stuntery...
That said, the strangest fretless bass I had was an unlined fretless with dots at the fretted positions: simply a nightmare to play as each time I looked at them, it blocked me as my ears were telling me I was in tune when my eyes were saying I wasn't.
I ended up giving it to a school after having masked the frightening dots and putting some fluorescent dot stickers to the usual spots (3, 5, 7, 9, 12...).
The funny thing was that it was sounding vey well...