I kind of naturally have to say bassoon since that is the instrument I enjoy playing the most and is my main instrument.
However, you could say I'm a real woodwind/brass enthusiast. Particularly on the woodwind side. Aside from the bassoon I also really like saxophone (tenor being my favorite) and oboe/English horn. However, I'm really pick with the saxophone. I think it can be really beautiful, but I don't believe that it always is. Particularly I really dislike its general usage in rock music. I know that rock music isn't supposed to be beautiful, but they can really make the instrument sound awful IMO. On the flip side I typically love bands that have a consistent wind section in their songs (like Chicago).
So, yeah, I really love a band that has a consistent wind section. That can make them so much more awesome because woodwind/brass instruments are awesome. lol
I also love some keyboard instruments - Piano, harpsichord, and organ are all pretty awesome. I also really like cellos, and also double bass in jazz. I love walking basslines.