I massively prefer 38mm-wide necks. I play them over 90+% of the time, as all of my basses, but one, are that width.
When I play my Cutlass, with its slightly wider string spacing, it throws me for a while, before I get used to its ergos and I need to consciously adjust to them. Having a gorgeously thin neck profile, as it does, really helps accommodate me to the change, but its slightly wider string spacing difference compared to a 38mm nut width is real, at least for me.
I had the same problem as the original poster. I started out with a Fender P bass and found the neck to be too large for me.
I switched to a Fender Jazz bass and it worked much better for me. I still have to make micro shifts with my left hand but not near as much on the Jazz bass.
Go to the music store and try out a Jazz bass. I think you’ll be pleasantly surprised.
Good luck!
You can get Ps with Jazz necks. Jazz necks (38mm nut width) are quite popular and are on many configurations. The new Rascal I have has a Jazz neck which is thin and very playable.
Why does almost everybody say “this sounds better than that”? This is an electric instrument, not a violin! Comfort, play ability matters more. Heck, change the pickup someday if you want. But only you will probably hear the difference. I bought my Ibanez as soon as I put it on, so comfy. Never looked back.
Not necessarily.
I have two Fender Jazz basses. I really like my Geddy Lee Jazz neck. It is thinner than my American Professional Jazz neck, and it is a solid maple fretboard. The Geddy Lee is MiM, but I like playing it more than the Am Pro specifically because of the neck.
Nothing wrong with MIM. I have an Ibanez MDB5 Mike D’Antonio signature bass with a fantastic neck. Sometimes signature basses have neck profiles you just can’t get elsewhere.
I can’t find a flaw in my MIM Mustang btw.
I don’t either. I like my GL!!! It is heavy, but I feel guilty liking it more than the American made Am Pro—like I am just not good enough to appreciate the difference. 
Be proud of your Geddy lee. Rock it!
My sister drives a Subaru. She has done well for herself and could afford a Ferrari if she wanted. Her 10 year old Subaru fits her, and she’s happy.
Ibanez, Schecter and Sire are all nice and slim in my stable.
I am a thin-necked-bass fan. Always have been. What kept me away from (and keeps me away from) the Fender p-bass is the chunky neck. A Fender j-bass neck is about the thickest I like to go.
As @Wombat-metal mentioned above, the Charvel neck is sublime, but my favorite of the “thin-necks” are Ibanez. Specifically, around the SR-500/600 range, although the SR-300 range has great necks as well (they’re just maple/walnut and have a different tactical feel to the jatoba/walnut of the SR-500s/600s). They’re both 38mm width at the nut, 19.5mm thick at the 1st fret, 21.5mm thick at the 12th fret, with a 305mmR radius.
Just an aside: I’ve got a Sire MM P5 and its neck is thinner than my Fender Jazz. I don’t have the measurements handy but from my 100% reliable “hold the fingers around it and move from bass to bass while trying not to move my finger positions” method of measuring, it’s the thinnest neck of my basses. P bass sound with rock bass neck. Gotta love it.
Sire is a brand I’ve NO experience with, other than looking at them on websites. I’ve never even touched a Sire.
Heard they’re pretty damned good, though, and would very much like to play one in person.
Sires have great builds, materials, finishes and playability, no doubt. A lot of value that punches way above the price tag.
They’re definitely worth checking out, if you get a chance.
I gotta go with @JustTim on this. I love the feel of my Ibanez, and it’s just the sr-300. But i can tell you it’s a really great feeling neck. (For me that is-everything is subjective)
The only thing I’ve found i like playing more is my daily player-the schecter custom 4.
I went to my local music store and tried to get on the fender bandwagon and just couldn’t flip the switch. Those necks feel like playing a 2×4 to me-but again, subjective.
Well, that and the 300 dollar switch. That little toggle switch that switches it from active to passive mode ups the price 300 dollars. I wasn’t able to rationalize that.
The SR line broadly have similar necks and they all feel good to me, every one I have touched. Yamaha basses tend to be similarly slim with a nice 38mm nut width neck on the TRBX line, and the BB is a little thicker (and has a 40mm nut width) which I actually find even more comfy - 40mm is a nice compromise middle size.
I don’t know why 40mm isn’t more popular. I prefer it, though most of my basses are 38mm or 42mm. It’s really comfortable, and on an ESP thin U profile it’s a glorious neck.
Yeah it’s really good! My SBV is 40 and so was my BB. Feels great, my fave too.
It’s absolutely subjective I agree. However within the Fender range there’s quite a difference in neck profiles. I have small hands (size 8 ski gloves) but the Fender player series feel quite slim to me. I can wrap my hand round it all the way up the neck. Conversely I tried a Fender Vintera Bass and the neck felt a lot bigger. So they’re not all the same.
Curious why nobody has discussed the elephant in the room.
I love that guy
