It is difficult to determine which node service provider is the most stable, as different providers may have different strengths and weaknesses depending on various factors such as network size, node infrastructure, and uptime guarantees.

Some popular node service providers include Infura, Alchemy, QuickNode, and Bison Trails. These providers offer a range of services such as Ethereum, Bitcoin, and other blockchain nodes, and may differ in terms of their pricing, security features, and customer support.

When selecting a node service provider, it is important to consider factors such as reliability, security, scalability, and customer support. Additionally, it may be helpful to read reviews and compare different providers based on their reputation, track record, and user feedback. Ultimately, the choice of a node service provider will depend on the specific needs and requirements of the project or application being built on the blockchain network.