There`s a good few that I regret parting with, none that it really hurts but my Mex Strat that I had from 1995 til about 2015 - I sold it cos I wanted to play solely bass for my band and not get distracted by any other instruments, looking back I had it for 20 odd years, didn`t need the money so should have kept hold of it. I also regret moving on my Gibson Les Paul Studio, it was a great guitar but again, moved it on when I joined a band and wanted more basses - more than I needed for the band. Should have been disciplined but never been my strong point. And my Gibson Les Paul Bass, and my MIJ Fender 51 Precision Reissue, would be nice to have kept them.