#1
I know that preference comes down to the individual but it seems that Martins are generally considered to have a fuller/warmer/muddier sound with more bass while Taylors are considered to have a brighter/thinner sound.

What about the build of each brand causes the difference?
#2
Depends on the tonewood used, there's many articles out there that compare them. Strings also matter but that's you choice of what to buy.
#4
^ Yeah. I'd say that the biggest difference is caused by the bracing. Yes, tonewood plays a big role, but by changing the bracing, you can make a mahogany side/backed guitar bassier than a rosewood guitar.

Taylors also all come with Elixirs so that also plays a big part in it.
Equipment:
- Art & Lutherie Cedar CW (SOLD! )
- Martin D-16RGT w/ LR Baggs M1 Active Soundhole Pickup
- Seagull 25th Anniversary Flame Maple w/ LR Baggs Micro EQ

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#5
Another difference is the shape of the guitars that make their famous sounds. At least, for me, I associate the martin sound you're talking about with their dreadnoughts -- even though they make guitars that sound much brighter and sweeter. With taylor guitars, they make dreadnoughts too, but more often we see grand concert or grand auditorium shapes -- the narrow waists reduce the surface area of the soundboard and bring up the treble which results in a brighter or, at least taylor argues, a more balanced sound.

Most big guitar companies make something for everybody