I also go for alternative rock music, but for now, let's talk about classical music.
I was exposed to classical music sine I was around 13. I fell in love with it, especially the violins. After years of listening and experience, all I can say is that there is no recording nor performance that is exactly the same. It's like I tend to only prefer this version by this specific artist. Other versions, they're not welcome to me. I am very explicit and choosy to who performs them. I developed a classy taste on specific performers. To name a few:
to enjoy them, you need to set it in high quality
- Beethoven's 9th Symphony: National Youth Orchestra, et al. performed at BBC Proms 2013 - Young and fresh performance :)
- Vivaldi's Four Seasons and La Stravaganza: Europa Galante - I love how they played it naturally using period instruments as it was originally intended.
- Bach's Goldberg Variations: Glenn Gould - He has a unique way of playing pianos
- Paganini Caprices: Julia Fischer
- Canon in D: Voices of Music - Played in original period instruments
Classical music is a very large world. Generally, I'm more into the early periods of classical music, the Baroque ones.
Antonio Vivaldi tops my favorite list of composers. I actually named my phone on him! His style in music keeps me focused when I listen to his works.
The second one is Wolfgang Amadeus Mozart. He's someone you might be familiar with. I named my first smartphone after him. I usually refer his pieces in catalog numbers, like KV 620 - The Magic Flute, and KV 626, his last work Requiem Mass in D. Mozart has a very distinctive 'theme' or 'trademark' in his compositions that lets me know that it is him who composed that once you hear it.
Other composers I like are Bach, Beethoven, Corelli, Tartini, Monteverdi and Handel.
But wait, there's more!
Original motion picture soundtracks can be considered as part of classical music. I enjoy most of the music of John Williams (That includes the music of Star Wars, Harry Potter, Schindler's List, etc.)
A guide to beginners
If you are a newbie in classical music, I strongly recommend you watching BBC Proms videos on youtube. They're really great examples and they got excellent performances.