IP2World

Oxylabs is a premium proxy service provider offering a comprehensive range of solutions including residential, datacenter, mobile, and ISP proxies.
They focus on providing reliable, high-performance proxies with advanced features for web scraping, data gathering, brand protection, and other use cases. Oxylabs has one of the largest proxy pools in the industry with over 100 million residential IPs.

Smartproxy is a proxy service provider established in 2018 that offers residential, datacenter, mobile, and ISP proxies.
They have a large proxy pool with over 55 million IPs across 195+ locations worldwide. Smartproxy provides solutions for web scraping, data collection, ad verification, brand protection, etc.

IPRoyal is a premium proxy service provider offering a wide range of proxy solutions including residential, datacenter, ISP, mobile, and sneaker proxies.
They focus on providing high levels of online privacy for unrestricted internet access. IPRoyal's proxies support various use cases such as web scraping, social media management, brand protection, market research, testing, and automation.

Shifter founded in 2012, specializes in residential proxies. They boast a large pool of over 31 million rotating residential IPs worldwide. 

It offers both backconnect rotating residential proxies and static residential proxies, allowing for customization of location targeting and rotation time. Shifter is an excellent choice for those needing a vast residential IP pool and not overly concerned about price.