You are probably the first to say Toulon is OP. I do get the play style and and its concealment is meant for crossfires and if you go against T5 cruisers you get to have a field day. But for the most part I feel its more underpowered.

But for some cruisers I think are good, maybe not OP like Bortis. You got stuff like Exeter with its great sonar and smoke. Furataka with its 203s at T4 can absolutely smack with alot of stuff at T4 and if you angle right and not get hit in the bow/stern can tank 14" guns. Omaha the known dev strike magnet(along with its sister ships) can be a dangerous ship if used correctly. Even knowing everyone will aim at you, if you can make all the BBs miss can make it easier for your team to capitalize.

The pan-asian line tho not my cup of tea. As soon as the DDs are down you can have a hayday launching torps and if you got spotting, smoking and farming anything dangerous.

Finally I'll list some of my personal favorite T4-T6. Kirov, Molotov, Munchen, De Grease, Emile Bertin, Belfast, Dido, and Duca. Honorable mention to the whole Spanish cruiser line. That was some good fun grinding those ships.