Forget it. Not as useful as it sounds from all accounts I've read.
What's worse, the full dyson set will get you killed faster than any other set. The shields aren't that great, but they have these quick little heal processes afterwards. So the end result is it feels like your hemmoraging hull points through full shields -- because you take damage, the shields suck so it goes to your hull, and then the shields bounce back. Instead of having full shields that actually help, you get paper thin shields that heal real fast.
It leaves you vulnerable and you just lose hull points and die with full shields.
Not 100% accurate, but that's the dumbed down version. Practically speaking, the Dyson set sucks.
The new Solanae shield & impulse are probably the best you can get outside of STFs. The shield is practically the cool little brother of the MACO XII shield lacking the additional +20% vs. plasma. Add a good purple positronic XII deflector with +shds & +stl to it and you're more than save for any endgame activitys you'd like to do.
The Reputation Dyson set is for science characters. Other characters would be better off using something else.
The "New" Dyson set from the anniversary missions is good, but not as good as MACO. I'd imagine that it will become better once the anniversary ship has access to all those additional shield heals from the consoles.
The Borg set is incredible, especially when used on a Tactical officer. This is for DPS. Personally, I like the borg shields. Fleet shields might be "better" to some people, but I like the fast regen of Borg.
MACO is the definitive tanking set (a case can be made for Nukara), as long as you don't use plasmonic leech. If you want to use Leech, then swap MACO shields out for Fleet.
Sardak (Science Officer): Captain of a 23k DPS R'Mor Temporal Science Vessel, R.R.W. Vathos Patiently waiting for a Romulan Science Vessel