There is very little reason to restrict yourself to WebGL 1 anymore, but many existing projects are still on WebGL 1 because Safari didn't support WebGL 2 when they were written.
WebGL 2 is going to be the best option for a long time. While WebGPU is in progress it will be many, many years before it is supported anywhere near as widely as WebGL 2.
There is very little reason to restrict yourself to WebGL 1 anymore, but many existing projects are still on WebGL 1 because Safari didn't support WebGL 2 when they were written.
WebGL 2 is going to be the best option for a long time. While WebGPU is in progress it will be many, many years before it is supported anywhere near as widely as WebGL 2.