I prefer Both...for different reasons in different applications at different times according to different moods. Neither is better over the other. There's a Pickups and Electronics Forum on TB
Single coils lately, they give a clarity not present inregular humbuckers, but they make noise when soloed. So I would have to say, splittable humbuckers.
Single coils have a little more clarity and Presence to me over Humcancellers.John Suhr uses some good Humfrees in his basses that sound really good.All single coils seem to hum but if you can get your tone with both pickups balanced together I would go with single coils but the hum normally is only noticed between songs.Guitar players make ten times the hum with single coils than basses!
Suhr's "Humphrey" pickups do sound good. They are however not single true single coils - but rather actually humbuckers and the name implies. Suhr says there isn't a huge difference between his pickups but I disagree. I had the Humphreys in my bass and while they did sound good (and DEAD quiet), I recently swapped them out for John's true single coil pickup (the "Vintage") model. The difference is unreal - amazing pickups and I'm fine with the little bit of noise. There is nothing like a single coil, especially on a Fender style bass.
I think I'd take an awesome bass with soapbars over an awesome bass with singles. The margin of awesome would be small but there's a certain sound that can only be gotten with humbucking pickups that you just can't with singles, that and they don't hum. In addition, for the tones that I liketo get out of single coil basses, an awesome bass with soaps would be able to approximate it well enough for me.
I prefer soapbar and P pups. The humbuckers Ive played, those with the large exposed extra wide pole peices have all been overly trebly voiced without exception to me. Jazz type pups are better then those to me but Ive never really gotten a tone I really like with Jazz pups except for one exception with neck position jazz pup. So I vote neither jazz nor humbucker pups. And vote for soapbar and P pups as the ones I really like. Yes some soapbar pups can do a jazz pup simulation minus hum, but these also do their own soapbar voice too. I do however prefer soapbar pups that in addition to their own soapbar pup voice also do nice P pup simulation.
I find the only pups for me are double hums with massive poles such as what is found in G&L and EBs. I dont avoid treble...I go looking for it!
Big, fat, meaty MM-style humbuckers. And you can split the coils!! (there is a recent discussion about this in the P/U forum....a split coil will not have the output of a true single coil, but it's good enough for me).