I really liked this video released yesterday by USEA about judging FEH. It was helpful to hear what the judges should look for, especially about gaits and movement. Regarding “flashy” trot, they noted to watch how the horse moves behind, and not be fooled by expressive front end action. Look for ability to collect and extend, but value correctness as much as bounce.
I appreciate what Robin Walker said about the trot/canter-- a fancy trot will win you points in dressage, but the bulk of an event horse’s job is done at canter. And it’s too much work to have to “manufacture” a good canter for the horse’s whole career. When the horse has a naturally good canter, it makes everything easier.