Chazmek
Sorry if that seemed flip. It all depends on how good you are on 'absorbing'. If you can really do it, than you must pick a healthy tree, not just any based on that you 'like' it. Think of it like a sexual partner, just because you like women doesn't mean you'd like one with HIV...

Willows? Cool, the bark of white willow contains salicin, which is a chemical similar to aspirin (acetylsalicylic acid). It is thought to be responsible for the pain-relieving and anti-inflammatory effects and has been used for centuries . That's the good. For the bad, see above.