Which modern calligrapher writes best?

You can't say that. What's the best? Personally, I most agree with Zhao Puchu's regular script skill, but! Remember but! Different artists have different understandings, and different art collectors have different understandings. As far as I am concerned, what I want most is the different works of the following two masters.

For example, the Heart Sutra written by Guan Jun, the director of China Calligraphy Association and a famous calligrapher, is elegant in font, calm and complacent, and has won the essence of the Heart Sutra, which is very excellent.

Another example: Zhuge Liang, the banner of the famous old calligrapher Zhang Jieshu's Teacher's Watch, is dignified and neat, sincere and rigorous, depicting Zhuge Liang's self-denial and helplessness in the situation, and is equally excellent.

In fact, there are many experts. Look more.

I hope it helps you.