microservice communication, sync versus async?

hey everyone, i'm working on a new microservice architecture and hitting a common crossroads. we have several services that need to interact, and i'm trying to decide on the best communication pattern. for some interactions, synchronous calls (like REST APIs) seem straightforward. but for others, asynchronous communication using message queues (like Kafka or RabbitMQ) feels more appropriate to avoid tight coupling and improve resilience. when do you find yourself leaning towards synchronous calls, and what are your criteria for choosing asynchronous patterns in your microservices