Re: Jazzmaster or Jaguar?
The main differences between the two is Scale lenth. Jag is 24", Jazzmaster 25 1/2". And also the pickups (obviously), Jag having Smaller strat style pickups (not actually strat pickups but around the same size) which are a tad mellower sounding than strat pickups, And the Jazzmaster haveing large p-90ish pickups, Although the jazz pickups are a Bit plunkyer than p-90's (think a cross between a strat and a p-90). Also The Neck profiles are a bit different. Other than the obvious differences that scale lenth has on the feel, The Jazzmasters tend to have a thicker neck, were as most jags have a skinnyer feeling neck. So if you have small hands you might prefer a Jag neck, or if you have big hands you might Prefer a Jazzmaster neck.
Other than that its mostly cosmetic differences. The jag obviously has the three metal control plates, and slightly different switching than the jazzmaster.
The jag has three slider switches on the lower control plate, which turn pickups on and off individually, and the third selects the "rhythm" circut. The rhythm circut (which is pretty much Identical on the jag, and jazz) is located on the upper control panel, and Is pretty much a "preset" tone/volume contol, so ya can have a secondary sound with the flick of a switch.
Quality is gonna be pretty much the same between the two. If you were to go with an american made version it might be slightly higher quality than the japanese version, But not by much.
I've owned A few Jazzmaster, and a few Jags. Japanese and american (I always bought em used though), And Honestly theres Not Much difference in quality. The Most notable difference is in the wireing. The japanese versions tend to have Crappyer pots/switchs/jacks, and the soldering tends to be sloppyer. And the actual wire used to wire it up is Thinner and cheaper on the japanese. The American pickups don't sound Much different from the japanese pickups really. Another difference is the Bridge/trem. The american Bridge on the Jaguar comes with a "Mute" thingy, and the japanese bridge doesn't (at least not on any I've seen/owned). But thats not really a big deal being as most people tend to take those off anyways. And the American trem tends to stay in tune a bit better than the japanese, but neither has much tuneing problems. And if you lock the trem its not really important anyways.
I can't really recommend any good Upgrade jazz/jag pickups, cause I always replaced mine with buckers. Cause I really don't like the jazzmaster or jaguar pickups, or most single coils really.