AMI has 3 Syllables.
This account preaches the truth, the whole truth and nothing but the truth about 3 letter products (not officially affiliated with AWS)
E-C-S - Elastic Container Service - Not eh-ckes neither ee-cees nor Ex (People would be wary to use a product named Amazon X - they might think that AWS is taking after Google with their Alphabet) #3syllables
E-C-2 (Well is should actually be E-C-C - but EC2 sounds so much sexier) Elastic Compute Cloud - Not ek-2 (or even eck - other people might get confused with "what the heck2") #3syllables
E-K-S - Elastic Container Service for Kubernetes - pronouncing this x-kay (ECS-K) would sound too much like Xray (another AWS product). Also see above about E-C-S #3syllables