We have tested the following eSim for performance and reliability in China. These eSims have excellent performance with good value in pricing. 

1. Airalo: Airalo is  a strong eSim provider. Airalo does not support unlimited eSims in China at this moment, but we recommend purchasing the highest amount of data you can buy from them if you end up staying more than 2 weeks. You will receive 15% off for your first eSIM (if you click the link in red) and 10% sitewide if this is not your first eSIM with them.
2. Nomad. Nomad eSims have stood the test of performance pretty well in many countries we’ve traveled to, including China. Sometimes they run sales that make eSim purchases very affordable. Verify and compare at the time of purchase to see if their eSIM has the best value. But in terms of performance, we can upvote for it.