French horn for about 3 months in seventh grade (1968), got sick of schlepping the bloody thing. (Ever try to carry a french horn case 1.5 miles to and from school? Your leg banging up against that case every other step tends to want to divorce you.) Wanted to quit band, but the band director talked me into trying the trombone, which I stuck with through the rest of jr. high and high school. Taught myself "baritone" along the way in three clefs, though I still struggle a bit with alto clef. Graduated from high school and jobbed it for about 6 months, playing in a community band until I enlisted in the Army.
Stayed in the Army a full 20-year career, the last 17 of which were as a euphoniumist, trombonist, and really awful trumpet player (hey, don't laugh - I've got two bugle jobs under my belt - heh). Retired from the Army 18 years ago and I haven't put the horn(s) down since and have even picked up bass trombone and tuba along the way.
Euphin' is still what I prefer to do, though it's really, really hard not to fall in love with the best horn I've ever owned, an Edwards B454 bass trombone that practically plays itself.
U.S. Army, Retired (built mid-1950s)
Adams E2 Euph (built 2017)
Boosey & Co. Imperial Euph (built 1941)
Edwards B454 Bass Trombone (built 2012)
Boosey & Hawkes Imperial Eb tuba (built 1958)
Kanstul 33-T lBBb tuba (built 2010)