The best option for me is a comfortable camera strap that allows me to slide the camera front and back. This allows me to keep the camera on my back while riding, and I can qhickly slide the camera to the front when I want to stop and take a photo. A handlebar bag is fine if you need to store the camera or just don't want to carry it on your person. If storing the camera in handlebar bag try to get a bag that's big enough to keep the lens attached. Taking time to attach a lens means you may miss the shot (depending on the subject and how fast the light is changing).

I use a BlackRapid strap that's about 10 years old and it's built like a tank. It'll last at least another 10 years (probably longer) so I'd say they are a very worthwhile investment. https://www.blackrapid.com/all/camerastraps/