Back end: Java 9 JVM, Spring Boot web service, Kotlin, plain SQL via JdbcTemplate working with Kotlin data classes, Liquibase for DDL and migrations, Spring caching with redis if need be, Postgres, deployment via docker to AWS Fargate
Front end: Angular... but I’d like to try Vue. Nginx and docker to Fargate
Anyone who knows Java/Kotlin will have experience with Spring Boot so it's easy to find good people. The whole platform is as mature as it gets at this point and the docs/questions cover pretty much everything.
It's really easy to get started when working on smaller projects, but you can also easily scale and integrate loads of other technologies if/when you need to. You might not need a complex caching layer, monitoring, metrics etc when you're starting out, but you know you can add it in if needed.
I cannot wait for full ES6 support in vue - it will get massively better by then.