This is such a personal thing. I believe that hand size and playing style both are important factors that influence our preferences on neck thickness and string spacing.
I play mostly 5 and 6 string basses when I play electric but about half the time I play upright bass. I have fairly small hands.
The electric basses that are the most comfortable for me to play are my Peavey Cirrus basses. They have tight string spacing at both the nut and bridge and the necks are fairly thin front to back. Those basses also have superb fretwork and set up with very low buzz free action. When I play them I have nothing about the bass that distracts me from the music.
That said, I also own a Roscoe Century 6 fretless, G. Gould ggi5 and ggi6 and a Music Man Bongo 6. The string spacing at the bridge is a little wider on the Roscoe and Gould basses but the width at the nut is comfortable and the necks are not too thick. The Bongo is a challenge for me since it is much wider at the nut than any of my other basses. The width at the bridge is fine but that wide nut takes a bit of getting use to. The 34" scale (all my Cirrus, Gould and Roscoe basses are 35") and the thin neck on the Bongo still make it fast and comfortable to play but I am aware that it would be a better fit for me if the nut were less wide.
I also own a lovely USA G&L M 2500. It has a deeper neck but is very narrow at nut and bridge. It is a very fast feeling neck.....yeah....fast. Just very easy to get around on and the neck sets up with low action due to the plek job (the Gould basses also are plecked and set up quite low).
Perhaps we overthink these things. I never hesitate to play my Bongo because the neck is wider at the nut. Every one of my basses sounds and plays great and I enjoy them immensely.
Time to practice, isn't it? Oh look, the Bongo is right here on the stand!