[Anguirel]

The problem with Turin is that he's off the scene, heading for Dor-Lomin to mangle all the Easterlings he can find. So his death wouldn't really effect things much.

(You'll notice that I tend to implement evictions by death. This is because eviction is basically going to Mandos/the Void, and death is a direct and satisfying way of getting people there...)

We have to decide where Morgoth is likely to strike, and therefore where we should undermine resistance.

He does not know the location of Nargothrond or Gondolin, so that rules out:

Idril
Galadriel
Finduilas
Gwindor
Celebrimbor

as candidates. This leaves his probable targets:

Sirion. The second-last male of Fingolfin's house, Ereinion (the other being Maeglin) rules there. A literal haven for displaced Elves. He knows where it is too. But it's very difficult to reach and requires effort to assault.

Ossiriand. His three most determined enemies, Maedhros, Maglor, and Celebrimbor, lurk here. However it's a vast area and would require guerilla warfare of a sort Morgoth's minions have never been successful in, fighting against a combination of the best Noldorin warriors left in Beleriand and the stealth of the Green Elves.

Doriath. His most powerful enemy Melian resides here. The area is deeply divided, with a war going on between Olwe and Dior, and Melian's destructive neutrality. It is a known haven of Elves and of Men in Brethil, on whom Morgoth is particularly eager to impress his anger. His missing Silmaril is here. Doriath can potentially seriously hamper attacks on Sirion or Ossiriand if allowed to stand.

It seems then to me that Doriath is most likely. At Doriath the heads of resistance will be:

Dior
Olwe
Celeborn
Melian
Mablung

(Note in passing: don't worry about evicting people before their offspring appear on the list. It's such a bore having to scrap genealogical lines that I almost never do it, so the child will often replace the dead parent.)

From that list Melian is the most powerful enemy, though Mablung might also be considered-great archers can be deadly to Dragons...

So, in conclusion-

++MELIAN