I've been trying to decide mine. And y'know what? I can't decide.
I love guitar. no surprise there, as I (used to) play one (badly). But .... what type? Depends on my mood, ranging from Clapton or Carlos Santana (among many) to John Williams (guitarist and member of Sky, not the film score composer) and Segovia dueting Spanish Guitar.
But then, I love violin (used to play that too, very badly) be it the Coors or the violin lead in Bach's Brandenburg 2.
Oh, and a really good church organ playing Bach classics, especially the oh-so famous if disputed in name Toccata and Fugue in D minor, or Rick Wakeman. Used to play organ, too. But typically electric, nit Church. Still got a 80s/90s era Yamaha. When I think of what that cost, back then .... yikes.
And Saxophone? Makes the hairs on the back of my neck stand up. Like, oh, the sax solo in Al Stewart's Year of the Cat.
Or trumpet. I adore the solo section from Aida, but the trumpet sections in Branderberg 2 are .... just epic. Especially when done using the original design of trumpet, from Bach's era, i.e. valveless.
But then, I listen to Tubular Bells and the way the magic emerges from layering multiple sounds .... in so many musical works, be they classical, pop, rock, whatever, you can often struggle to pick out bass instruments whether bass guitar, double bass etc, but in fact they're the glue that holds everything together. And that bass rhythm in Tubular Bells is hypnotic.
So ... what's your favourite? 'Cos I'm beggared if I can decide. I love 'em all.
Oh, and talking about layering, anyone see that TV prog about John Williams (the film score composer not the guitarist) when the full symphony orchestra playing the Star Wars theme? That demonstrated it perfectly.