With electric guitars, the majority of tone comes from the pickups, and so guitar builders have a wide choice of woods they can select. There is very little difference in tone when using these exotic woods on electric guitars, and for most people, it's not something you'd notice. In general, heavier, denser woods will give more sustain but will be heavier to hold too, so it's a fine line that builders need to walk between weight and aesthetics. For acoustic instruments, the wood choice will make a massive difference in tone, especially the choice top. The back and sides have less of a part — but still important — to play in tone, but the top is where the magic happens! Exotic woods do not necessarily sound better or worse, but will certainly sound different. The only way to make a real assessment is to play guitars with different tops alongside each other, and see what sounds good for you.