I'm a western rider, but the trainer I used for a few months was an English person, so I was required to learn a lot of the basics in English. I know how to post and do a sitting trot, and for me, it depends on the horse. My lesson horse had a horrible bouncy trot due to huge strides and you could never slow him down enough to sit it comfortably, he wasn't very big, but for some reason he had large strides. My dad's gf's horse that I ride often is a WP mare that was trained correctly, and her jog is quite comfortable, but out of habit I start to post if I ask her to extend her stride and speed. On one of my own horses, you don't even realize he's trotting because the gait is so smooth, while on another you absolutely have to post.
So for me it depends on the horse, but I usually prefer to do a sitting trot, just because I feel more connected to the horse, just like you said.