Action camera for motorcycle - GoPro or something else?

For a motorcycle I'd suggest looking at the DJI Osmo Action or even an older GoPro Hero 11 - they're mounted more stably and have better image stabilization, which is really important when you're riding. If you're riding a lot in the rain or dealing with heavy vibrations, you need something with solid waterproofing (at least IP65) and a mount that doesn't keep slipping.

Here's the thing: the mounting makes all the difference. GoPro itself is fine, but the standard adhesive mounts don't always hold up on longer trips. Invest in a proper helmet mount or handlebar mount with a safety cable - this isn't marketing BS, it'll actually save you a lot of headaches. DJI Action takes up less space on your helmet right now and has a touch screen, which sounds annoying, but if you ever need to quickly adjust something later, it's really handy.

My tip: check out test videos showing how these things perform at high speeds. At 120 km/h the footage shouldn't be shaking too much. If you're staying under 200 euros and not riding daily, a cheaper action cam will do the job - but then you'll have to deal with somewhat weaker night vision. What exactly do you need anyway - more road recordings or really rough conditions?