The frets you choose say a lot about the kind of player you are, or at least the guitars you’ve grown used to playing over the years. Most guitarists of the past 60 years or so gravitated towards either a Strat or a Les Paul when they had the funds and this, with a few notable exceptions, tends to be where they stay. It’s not enough to learn how to play the guitar, you need to learn your guitar, it’s foibles, strengths, weaknesses and design flaws all affect your own style and sound and the first place this is noticed is the user interface… your frets and fret board!
Jumbo frets essentially mean that the pad of your finger will hardly ever touch the fret board, they act much the same as the scalloping does if you go for Yngwie’s style of fret board which means that with less friction you can play much faster but you have to learn to play with a very light touch as any excess pressure will knock you out of tune on that note. This setup is particularly nice when you have a medium tension on the strings and a low action, it can feel as if there are not even any strings there at all! The downside to this is that the jumbo frets often add as much as 1.5 to 2 millimetres to the overall depth of the neck… and if this doesn’t sound like much would you like it if you suddenly put on 10% more around the middle!?
The options mount up when you start considering lower smaller frets, the first benefit here is the width; a smaller fret means more of a curve and therefore much more accurate intonation overall than you get with wider, flatter frets. The lower height though means the fret board, and the friction it brings, comes into the mix. A slow and easy player will not be bothered by this but when you start trying sweep picking or Vai riffs the fret board material has a major effect. Rosewood and ebony have fairly open grain and can slow things down a bit, maples on the other hand are slick and fast, especially as they often have a lacquer finish applied which is the definition of slippery, especially when your fingers start bleeding (rock on!). Oiled boards have more of an effect, doubly so if it is allowed to dry out. If you play one guitar often you should clean the board with naphta or lighter fluid and re oil it every six months or so, this keeps it fast, playable and even keeps the tuning more stable on necks that have a lacquer finish. (a dry board is much more susceptible to atmospheric changes than an oiled one!)
Frets commonly come in three materials, two you’ll know about the third is used less but is a nice alternative. Nickel silver (which is actually brass and nickel with no silver to be found anywhere!) is the softest option and sounds warmer and more mellow than the others, always try and make sure you get good quality wire though, I have seen some cheap rubbish that can be dented with my fingernail! The next most used material is stainless steel, very hard and purported to last three times longer than normal fret-wire, it has a brighter tone though I struggle to hear the difference in blind tests and recommend you make your decision based on more practical things, like cost versus the money saved in the long run. My favourite option is hypoallergenic fret-wire that is made of, mainly, brass.. it is slightly softer than steel but still lasts infinitely longer than nickel/silver wire but the real reason to use it is that it looks gold instead of silver, when on a guitar with gold hardware this is just an amazing effect.
The final consideration is how shiny your frets are, like the fret board having smooth frets can really make a difference to the speed and nuance of your playing. If you leave a guitar on the wall for a year, or don’t clean your finger gunk off often enough, the frets will tarnish and the whole playing experience will slow down. It is easy enough to polish them yourself if you don’t mind masking off the fret board and getting busy with chrome polish and even general cleaning of the fret board with lighter fluid and lemon oil will help.
In the end your original choices of fret board and wire can change the character of your guitar but the upkeep of this user interface with have a much greater effect on your playing than you would think. Be anal retentive about your instruments setup and playability, it pays off in the end and both your playing and your guitar (though possibly not your guitar tech) will thank you.