My first 6-string basses were the "twins," matching fretted and a fretless Yamaha Pattitucci signature basses. I loved them and gigged them everywhere... then I bought my first F-Bass.
I've owned (and still own) Foderas, Alleva Coppolos, Nordys, Pedullas, Yamahas, a Carvin, etc., and they are all wonderful basses when we are talking 4-strings or 5-strings...
But when it comes to 6-string basses, the best I've ever played is F-Bass.
And I can back that up.
Fbasses have some unique advantages over nearly all other basses, advantages that make them the quintessential players' bass.
— Pickups
Some bass makers use other people's pickups, (Fodera, Pedulla, Roscoe, Mike Lull, etc.). Others design and use their own pickups (Sadowsky, Ken Smith, Nordstrand, etc.) FBass pickups are proprietary single coil stacks that play in either single coil or humbucking mode via a pull up coil tap control. Most of us prefer the single coil tone, but if you want a glassier tone, or need to kill a hum, you just pull up on a knob and you've got humbuckers. The thing is, Fbass gives you a choice: single coil or humbucking — in the same bass, and they get points for that in my book.
— Preamp
The preamp is likewise made by Fbass. It's famous for being "transparent" and nearly impossible to distinguish from the tone of the bass in passive mode when the preamp is turned on. The Fbass preamp is boost only and 3 band (bass, mid and treble). What makes the Fbass preamp stand out is how each boost is musical at any setting. You can't seem to make the mids honk, or the bass muddy or the treble shrill. You always have an organic sounding bass even when playing it in active mode.
Another unique feature of the preamp is the utilization of a "multiplying" EQ, as opposed to the more conventional cut/boost type. The signal passes through all bands in a single path, resulting in lower distortion, tighter correlation and improved definition, while enabling a wide range of sonic possibilities. Gradually boosting the mid band, for example, while the lows are already boosted, results in a smooth higher frequency focus, while not diminishing the power in the low band. This is partially due to the bandwidth designation of each band, which further lends to a more natural sounding preamp.
Things get even better when treble is dialed into the mix. The treble band on the standard preamp is designed to add sparkle, without engaging the more "nasal" upper mid-band tones.
— Scale length
I'm always going on about the genius of a 34.5″ scale. Both the Fender Precision and the Fender Jazz basses were 34 inches from nut to bridge, which was fine until people starting putting B strings on basses. To give the B more oomph, many luthiers began to make basses 35″. The trouble is, that didn't just tighten the B string, it tightened all of them. Many players don't like the tightness, especially on the C string of a 6 string bass… it just sounds too tinny and artificial. Plus the added distances between the frets near the nut fatigues your fretting hand faster.
And while American builders were hung up debating the pros and cons of integer measurements in inches, (34 vs. 35), the Canadians' use of the metric system must have left them not caring because George Furlanetto figured out that the sweet spot for electric basses is 34.5″. At 34.5 inches, the C strings are musical and the B strings are solid, and the extra half inch difference from 34″ scale just isn't a burden on the fretting hand. The 34.5″ scale length works so well, I am pretty sure I will never buy a 35″ bass again.
— String spacing
All Fbasses that I am aware of use the string spacing of the standard 4 string Fender Jazz bass: 19mm (3/4 inch). I am SO glad, because I go between 4, 5 and 6 string basses all the time, and having the string spacing standardized like that makes the transition minimal.
— Controls
Many players prefer the control configuration of a single volume control and a "blend" (a.k.a. "pan" and "balance") knob. The trouble is, blend knobs tend to give you just 3 tones: soled bridge, soloed neck, or both pickups on. The only exception I know of is the Audere preamp which treats each pickup's signal separately, preserving a STEREO signal throughout the preamp, and making the preamp in essence a little mixer which allocates sound in a smooth, linear way proportional to the knob's position, giving a bass the tonal variation it would have it had dual volume controls… like Fbasses have. Dual volumes are annoying because you can unintentionally mess up your tone by simply trying to turn your bass up or down, but on the other hand, you can dial up tones not available to most volume / blend basses. That is worth it to me and to a lot of other players who prefer vol/vol to vol/blend.
FBass builder, George Furlanetto, has this to say about blend knobs other bass makers put in their basses:
"The balance pot adds another resistor, so there is more capacitance in the signal chain, thus slightly reducing the high end (slightly noticeable). With two pots you can blend the amount of each pickup, whereas with the balance you can only blend the two levels in balance; you can never have one pickup on full and add a little of the other."
— Balance on the strap
FBasses hang on the strap in a unique way. The entire bass is shifted to the right (if you are right handed), making life a lot easier for your fretting hand. An additional benefit is the viewing angle you get on the upper frets, which is especially nice if you have a fretless, lineless bass like I do. It helps me play in tune.
— Quality workmanship
Actually, quality workmanship isn't unique to Fbass, but Fbass quality is right there with anyone else you want to name.
— Playability
Fbass truly is a players' bass. It plays very well, not just easily, and rewards players who have developed hand techniques to make their playing more musical.
— Tone
Here is a favorite clip of mine on YouTube of an FBass BN6. The player is an excellent bassist by the name of Dave Hughes.
If you can only have ONE 6-string bass, FBass's flexible tone, playability and everything else make it the best choice I know of.
Here are 4 of my 6-string basses:
And here is my latest acquisition: #7 of 9 replicas made of Alain Caron's bass.
Again, I own and have owned a lot of fantastic basses from the best builders in the world, and when it comes to 4-string and 5-string basses there are a LOT of builders I really love, but when it comes to 6-string, FBass stands above the rest.