is it recommended to use only Spring Cloud Gateway Yes because
Spring Cloud does not provide any out of the box integration with Zuul2. Gateway has many features that are not available in the public version of Zuul2 such as Rate limiting, etc. Also, with the gateway you can have custom filters defined per route and there are tons of built-in filters defined as well, which helps a lot to get started. Reference
Reference: I think SCG is the way to go due to the agreements between Netflix and Pivotal, with the former leaning more toward the spring boot/cloud ecosystem as stated in https://medium.com/netflix-techblog/netflix-oss-and-spring-boot-coming-full-circle-4855947713a0