So my big issue with the other ATOs is they do nothing to enhance the gameplay experience of the other ATs. Scrappers, Stalkers, and then to a lesser extent MMs and Brutes. All have unique ways to modify or enhance the gameplay. Having played almost every AT as a fully IOd 50. I can safely say, it is fun and exciting when my scrappers crit buff goes off, and to enhance that further, I can manipulate my attack chain to line up my big hits during that buff if I place the proc into a mid range attack that gets it to fire off frequently while not wasting one of my heavy hitters.
This sort of interaction and fun is completely lacking from a majority of the ATOs, when one of my defenders gets a heal proc, most of the time I couldn't care less. When my Dominator gets a Fiery Orb, its ... sort of noticed? Maybe.
What we need, is not stronger or more powerful ATOs for other ATs, though that would not hurt. Is more interesting ATO effects. Make blasters ST attacks have a chance to splash to nearby enemies, give Defenders a team wide +10% damage buff proc that stacks and announce it in big flashy red font for the entire team to see it wont be game breaking anymore then Assault, but it adds to the excitement of the game. Not this boring damage proc crap, sure at the end of the day all these effects are just more damage more healing, etc, etc. But make them unique, flavorful, and more importantly, fun.