Re: Basswood vs. Mahogany
Mahogany is usually heavier, and muddier in tone IME. I've never played a mahogany guitar that is what I'd consider "truly bright". Spanky? Yes. Balanced? Yes. Extremely versatile? Absolutely. But never truly top heavy in terms of e.q. More like upper midrangey, yet still thick, even in the most brash sounding examples. Old, new, vintage, U.S.A., imported, whatever. Mahogany guitars are never naturally bright to my ears. They can all get a tone that goes to mud very easily. I prefer mahogany guitars with low-output pickups and/or single coils, and the thinner, the better. Putting maple on top of it makes it much more thick and brutal sounding – usually too thick for my liking, though it is a great tone for some things. I love my LP Standard for that certain "mule kick" attack that it has, but I find it limited tonally. I think Juniors, Specials, and SGs are far more "alive" and versatile.
Basswood is usually lighter, and less girthy in tone, but also not super bright. It seems to me to sound like a slightly more smooth and "laid back" form of ash. They both have that "poppiness" and lightness about them, but ash is more lively IME. Real stringy sounding, like you can't really dig in and pull out as much "oomph" as you can from mahogany. But I like it, because it retains that aggression and "cut through" even when you're playing hard and loud. As such, it can handle thick sounding pickups much better than mahogany IMHO. (I can't stand the sound of hot pickups in a mahogany guitar!) Several of my favorite guitars have been made of basswood, including my Aerodyne Tele and my blue MIJ Strat.
In general, I prefer mahogany guitars for "vocal" parts and leads, and chunky rhythm. I prefer basswood and ash for snappy, bright, crunchy rhythm, or for piercing, stinging sounding leads. That's just a generalization, and I don't live by it as a rule or anything. But it's pretty much what I tend to do naturally when recording.