Few more tests of the same aggregate reports to gain better perspective. MySQL 5.6.27 was the clear winner.

RDS MySQL 5.6.27 T2 Large: 0m34.977s

RDS MariaDB 10.1.14 T2 Large: 0m38.097s

RDS MySQL 5.7.11 T2 Large: 0m40.408s

RDS MySQL 5.6.27 T2 Medium: 0m53.214s

RDS MariaDB 10.1.14 R3 Large: 0m54.946s

Aurora (6/4/16) R3 Large: 1m07.187s

If there is enough interest we can provide a fully reproducible test case for anyone else to try. Currently we are using reports our customers run to validate performance of various types of DBs.