There are basically two types of pickups for electric guitars: single coils and hum buckers; and they sound completely different. Leather guitar straps – Single coils tend to be softer and brighter (and electrical interference will cause them to hum); hum buckers tend to be louder and have much stronger midrange and bass response (and they don’t hum). In addition, single coils tend to have better clarity than hum buckers when played clean, but hum buckers tend to work better with overdrive or distortion (because they are more powerful). Single coils also tend to sound better in the neck position, and hum buckers tend to sound better in the bridge position (again because of the midrange response and the additional power).
There are a number of pickups marketed as single coils that don’t hum, including Leather guitar straps.
For the most part, those types of pickups are actually tiny, bright sounding hum buckers. They are made to look like single coils by stacking the two coils on top of each other, instead of laying them side by side. No matter what anyone tells you the only thing that really sounds like a single coil pickup is a single coil pickup.
I think a better way to solve the hum issue is to get a reverse wound reverse polarity (rwrp) middle pickup (Fender Custom Shop Fat 50’s have a rwrp middle pickup). That way, if you have a Stratocaster, for example, you will have single coil tone in positions 1, 3 and 5, but you will have no hum in positions 2 and 4. Alternatively, if you have a Les Paul, you could get hum buckers that allow you to split the coils, so that you can convert each hum bucker to a single coil with the flip of a switch (Seymour Duncan JB Model hum buckers have four conductor leads, so you can use them with a coil splitting switch). Either way, you can get the best of both worlds.
Among single coil pickups and hum buckers, there are many variations in how they are constructed and how they sound. Leather guitar straps, a pickup is a row of magnets wrapped in copper wire. So changes in the magnets and the wire affect the sound. Alnico V magnets are commonly used in single coil pickups, like Fender’s Texas Special pickups for Stratocasters and Telecasters; they are stronger magnets and have a sharper sound. Alnicos II magnets are more common in hum buckers, like Gibson’s Classic ’57 pickups; they are softer magnets and they have a smoother tone.
As for the copper wire, “over wound” pickups tend to sound louder and have more midrange and bass; pickups with less windings tend to sound softer and brighter