Want to practice Xingkai script, whose copybook is better to use?

It depends on your own preferences!

Here we would like to recommend to you:

The most common Chinese regular script font in the media.

Although it is written in calligraphy, the hard-pen calligraphy is similar to it, only the thickness is different. The strength, stroke order, and frame structure are all the same.

You can just open the browser and search for it

华文行楷

There will be a lot of information for reference, or you can practice for a while by taking a few screenshots.