You haven't specified which region or location your application will be deployed. If I'm in your shoes, first step I will do is
Region Availability Check the cloud platform available in my region
- This is also crucial if your country has specific data protection related rules and also if local support from your chosen cloud platform is required
Cost Estimation Use tools like AWS Pricing Calculator and equivalent tools(for GCP and Azure), do an estimation
Ecosystem Fit Choose a cloud that aligns with your planned technical stack (eg :- Database, Storage, Queues/streaming services etc ). Avoid multi-cloud early.
Team Skillset Leverage your team's current cloud/platform expertise to speed up dev cycles and reduce learning curve.
Pilot/Test Run Run small-scale POCs on AWS EKS, GKE, AKS with simulated load tests. Compare setup complexity, cost, scalability, and debugging experience.
GCP
As of I know GKE is one of the most popular service in the GCP tech stack(Also considering Kubernetes is originally designed by Google) and icing of the cake is , GKE is the most automated compared to other two and easiest to manage, which is critical for a startup without a large DevOps team. As of I know they also provide strong startup credits through their Google for Startups Cloud Program(not sure if they still provide it). Its the most developer-friendly and pricing also quiet transparent
Amazon EKS
AWS has there own container orchestration service like ECS. Unless you specifically need Kubernetes, ECS (especially with Fargate) is recommended in AWS as its simple and faster to setup, tighter aws integration, Lower operational overhead (Fully managed), more cost-efficient for small teams/startups.
In my best of my knowledge, Setting up Amazon EKS is bit more complex and require experienced engineers(managing VPCs, IAM, networking, load balancers, etc.as it requires managing VPC, IAM, and load balancers carefully, which can increase operational complexity as well).
So long story short, requires a steeper learning curve for EKS setup— managing VPCs, IAM, networking, load balancers, etc., Needs knowledge of Kubernetes concepts, often involves building and maintaining CI/CD pipelines, observability stacks, autoscaling rules manually.
Generally AWS recommend EKS only,
if you’re migrating existing Kubernetes workloads (like lift-and-shift from on-prem or another cloud).
If you are using CNCF tools(Helm, Istio, ArgoCD, etc.)
You want multi-cloud portability or hybrid deployments (on-prem + cloud).
Your team already has Kubernetes expertise
I don't have much exposure and experience on Azure platform, so I will let others answer on that topic.
Wishing you all the best as you assess your options and choose the platform that works best for your goals. And don’t forget to let us know how it went and which platform you ended up choosing!