How spend our stardust?

It would help answer your question if you listed the pokemon you currently have with their IV's and moves.

One reason why I never thought it made sense to have so many defenders...I never had more than 10 so aren't as worse off now....

With my 10, I was mostly able to collect usually 8-10 daily...if a few gets knocked out overnight.

Just look at the gym raid boss counters list and see what you don't have. For the tougher tier 4 raid bosses where you need more people, it's pretty much just Machamp for now.

Catch tons of mons or hatch eggs.

I'm powering up and TMing only legendary counters such as Tyranitars and Golems. Dust just got real precious since new gym system where you don't get dust as reward anymore

In my opinion, PoGo has almost always favored attackers over defenders...now with raids and plentiful amounts of rewards from lv3+ raids, attackers just became every more useful. I also recommend getting about 5-10 mons to an above average CP level instead of using up all of your stardust just to get between 1 and 3 elite mons while the rest suffer from low stats. It's good to have some diversity in your attackers.