Like a lot of people, the freedom to listen to whatever music I want at whatever volume I want and to sing along if I want to is something I just can't get anywhere else.
I'm a bit of an audio buff. I wouldn't call myself an audiophile by any stretch, but I definitely have a base line quality that I strive for in any sound system I own. My old Civic had a Pioneer double-din deck with a 7 band EQ, Infinity Kappa components up front, Pioneer 6x9s in the back, and a pair of these in the trunk (10" Premier subs, 600W RMS 1500 Max). The speakers ran on a 760W Pioneer amp up front, and the subs on a Twister F2-500 (1260W) amp in the trunk.
This year I moved from the Honda Civic to a Toyota Tacoma and put a 16-band Pioneer DEH-80PRS deck in it. The rest of the sound system is still the factory "JBL Premium" stuff, but I'll replace it eventually. Quality is good enough for now, but I miss the punch from my old subs.
Both vehicles have a manual transmission, and this is probably my favorite part about actually driving. The Civic was a 5 speed, the Tacoma is a 6 speed. I love that feeling of actually being in control of the transmission. Driving an automatic feels weird because it shifts gears when it pleases instead of when I tell it to.
I love the raw power of the truck. It's only a V6 but that's plenty for what I'm doing with it. I love the capability to just turn off the road and find trails for my bicycle, or haul things that would never fit in the car in a million years.
TL;DR I love having the freedom to go where I please in a vehicle that is fun to drive and puts me in direct control. Everything feels a little brighter while cruising down a country road with the windows down and the music up.