I have a few:
My first was a pink Littman classic II that I got in college. I hadn't heard a heartbeat through a stethoscope in probably 10 years at that point, so the first time I stethed myself was really, really exciting
A year or two later, I bought an Allheart cardiology stethoscope, which was surprisingly good. I actually think I like it more than the Littmann classic II. Still one of my best. And so cheap! https://www.allheart.com/allheart-cardiology-stethoscope/p/ahdst0500blk/
A few years ago, I got a Welch Allyn Harvey Elite on sale for something like $75, which was a good deal, and it was the most expensive steth I'd ever tried. It's pretty good, I can definitely hear things through it that I can't hear through my other steths, but a bit uncomfortable for long periods
Not too long after that, I bought a Littmann Master Cardio - it sounded like one of the best stethoscopes out there so I sprung for it (also got a good deal on this one). Although I prefer the two sided design, this is a great steth. I think it's a bit louder than the Harvey Elite, just as clear, and super comfy eartips.
I think this is a pretty good collection for now, but if I know myself, I'll probably buy some more eventually 😉