If you are engaged in scientific research or want to go abroad, mathematics is the best choice. The rate of going abroad for basic disciplines is high, and foreign countries also need domestic talents for basic disciplines.
If you are looking for a job in China, communication engineering is the best choice, followed by the other two. Mathematics is the worst job in China, but you can transfer to many majors such as computer, communication and even management. It is a bit difficult to transfer, but you will have great potential after you transfer. Basically, you will become a leader. I switched from mathematics myself, and I feel that the foundation of mathematics is very helpful for my personal development.