In high school, I used a YBB-201 (the 3-valve, BBb version). The school didn't have much (any) money for instruments and stuff, so this was "the tuba" and more-or-less the standard issue tuba for our 25(?) high-school county. Well, except for the rich schools. They got the 321 with their fancypants 4 valves.
I started playing tuba in 9th grade, and made all-county and a bunch of other "honor bands" and stuff with that YBB-201. Didn't make all-state, but didn't poop all over the audition either.
But... I absolutely HATED that tuba. Particularly, the incredibly awkward size of it. Very tall. Not particularly "big" (i.e., very 4/4) for the amount of physical size of the tuba. That enormous hard case was obnoxious.
I think I was in 12th grade before I ever was live and in-person with another "real" tuba. Once, I sat next to a Miraphone 186 player (who was blatting the hell out of it and proclaimed the tuba as a piece of Shirt). Another time, in the 6 tuba section, I was second chair, and the last two chairs were from the "rich" high school. One guy had a Ziess BBb, the other a Cerveny Piggy. They also both proclaimed their tubas as being pieces of Shirt. I didn't like any of those 3 guys.
I played my YBB-201 well, and at the limit of what I was able to do with it.
When I got to college, I was issued a school-owned B&S PT-3, and I used that throughout college. Not a perfect tuba but ergonomically a WORLD better, and sound was about 2 worlds better.
After college, I first used a Miraphone 188 when I was on a band tour in Austria. Ergonomics were perfect. Sound was perfect. Intonation was nearly perfect. I was -- and still am -- blown away by that tuba. So naturally, I *didn't* buy a 188 for another 7 or 8 years... and then once I found a great 188, I sold that and haven't gone back to it. Sometimes -- like today -- I'm questioning what in the heck I'm doing to NOT own a 188.
I am what I am... and luckily, they've made lots of 188's. But never in my life will I go back to one of these tall Yamaha tubas, I can't stand them.