Pipa has hundreds of fingering, while guzheng has only a dozen fingering. Many sounds of pipa, erhu and violin depend on taste and position. The basic sound of guzheng is fixed, so you can play it directly. For beginners, it is easy to improve their interest in learning by playing guzheng at will, but it is difficult for beginners of pipa, violin and erhu to hear it. If you learn guzheng for 2-3 years, you can learn 10, which is a crash instrument. To sum up: Guzheng is the simplest.