If I had to pick one it would have to be my 1993 Gibson Les Paul Studio. Easily one of the worst guitars I own, but my father gave it to me. It was my first quality guitar. It's been through hell with me. It's headstock was snapped clean off and repaired. Its original black paint was stripped off and I applied a tung oil finish. Most of the hardware has been replaced over the years and I swapped out the original pickups for DiMarzio Virtual Vintage humbuckers. It's amazing what sentimental value will do to a person.