Choose a collection of Sith that would be on the All-time Dark Council. Any Sith in the lore is applicable. However just choosing the most powerful won't work as they would eventually fight and kill each other making them weaker. So they have to be open to team play as well has having political savvy while being manipulative and powerful enough to not be overthrown. The point is to create a lasting Dark Council, not a group of weaklings nor a group that will have too much ambition leading to infighting and/or singular rule.
The scenario here is that this hand picked Dark Council leads the Sith after running away after the Great Hyperspace War. Basically the same time as when Vitiate rose to power.
Off the top of my head I'd have Dooku, Revan, Marr, Caedus, Sadow. Maybe even Traya before she was betrayed.
I don't think anyone who followed Rule of Two principles would work on a Dark Council, so I can't see Dooku, Revan or Caedus playing fair.
Traya would also do her best to dismantle and destroy her "fellows".
Anyway my model Dark Council based purely on SWTOR era folks would be:
Military Offense: Darth Angral
Defence of the Empire: Darth Marr
Military Strategy: Darth Malgus
Imperial Intelligence: Lana Beniko or Darth Jadus
Production and Logistics: Darth Vowrawn
Laws and Justice: Darth Mortis
Ancient Knowledge: Darth Thanaton or Nox
Science and Technology: Darth Mekhis
Expansion and Diplomacy: Darth Serevin
1) Malgus (A relatively tolerant/open-minded guy and great asset in war)
2) Darth Revan(not a total d*** and a military genius)
3) Darth Plagueis ( Not a total d***, very wise and has immense knowledge in the force. He could even try to make the council immortal.)
4) Darth Marr ( He is also very wise and could help keep the council intact.)
5) Darth Bane(like some of the sith above, he doesn't just care about himself but the Sith Order's future as well. He could be a team player under right circumstances)
6) Marka Ragnos(Unlike some of the other Dark Lords, he focused more on keeping the Sith unified instead of blindly attacking the republic. He seems to be respected a lot by other sith and can help keep the council intact like Marr)
7) Dooku (He is an idealist and would work with others to achieve greater things instead of just pursue personal power.)
8) Darth Vowrawn (He is a chill dude and every council needs a weakling)
Basically this council has many members that are fantastic tacticians with political savy. We have expert manipulators, some members who hold more arcane knowledge but are less politically savy, and overall it is just a good mix of people. Although I don't doubt that one of them will kill one of the others sooner or later (which is almost inevitable for most Dark Councils) these guys for the most part will work together and would be completely badass
From all Eras:
Emperor: Darth Sidious
Emperor's Wrath: Darth Maul
Sphere of Ancient Knowledge: Darth Plagueis (Yeah, can't really think of anyone better for this)
Sphere of Biotic Science: Darth Wyyrlok (his knowledge of Krayt's armor and Vong tech would likely be great for an Empire)
Sphere of the Defense of the Empire: Darth Marr
Sphere of Expansion and Diplomacy: Darth Tyranus (The guy manipulated the entire Separatist Senate, and convinced thousands of systems to defect, and raise the largest droid army in history)
Sphere of Imperial Intelligence: Darth Cronal (I know not a Darth, but I think he'd be perfect)
Sphere of Laws and Justice: Ulic-Qel Droma (Not a dick, and would make be good for actually routing out infighting in the Sith and keeping order)
Sphere of Military Offense: Darth Malak (Good synergy with Revan + as equals less of a temptation to betray him)
Sphere of Military Strategy: Darth Revan (Can coordinate with Kun and Marr easily.
Sphere of Mysteries: Darth Traya
Sphere of Production and Logistics: Darth Vindicaa (Ventress as a puppet for Dooku, as I think his wealth and influence would be the best for this, but I also think he's better suited for Expansion and Diplomacy than anyone sans Darth Sidious)
Sphere of Technology: Darth Vader