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

1. Holafly: Holafly’s unlimited eSim plan is what you need when you stay in China for more than a few weeks. We have not experienced any interruption while testing it in China for months at a time.
2. Airalo: Airalo is also another 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. If you are staying for a month, Holafly comes up cheaper than Airalo. 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.
3. 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 performance, we can upvote for it.