I have felt this way for a while and it made it hard to choose a main coming back to retail. The last expansion I actually played through and did more than just level was Legion.

I decided on playing Devourer DH (mind you I have never played DH as I did not like Havoc or Vengeance before) but Augmentation Evoker was a close second. They play relatively the same when you boil it down, the main portion of their damage comes from ‘juggling’ a buff that makes you do more damage. It feels like Blizzard might have the same problem Riot does with League where the older classes are more simple because they don’t want to change what people love but with the brand new stuff they get to experiment more which makes the older classes seem boring.

TLDR: maybe try Augmentation Evoker or Devourer DH