by narsil0420
Yeah, Leadership and Lore have the most Gondor allies (four each) so, to me, that seems to lead me towards Imrahil, Denethor, and Boromir(new). However, you could try a tri-sphere Gondor deck using the resource movement abilities (and Steward of Gondor) to make it easier and even enable a deck that leaned more towards one or two spheres than trying to have all three spheres perfectly balanced.I like doing tri-sphere when I'm trying to make a thematic deck because it increases the amount of theme-related cards you can include.
I would then try
Boromir/Denethor/Beregond
or
Imrahil/Denethor/Boromir (old)
or
Boromir (new), Eleanor, Denethor
One important thing to remember is that it isn't as important to have a hero with high willpower because of the Seige and Battle keywords. You could possibly get away with a spread that had two good defenders and 1 good attacker and then use Faramir to boost your willpower if you get to a section of the quest that uses normal questing.
edit: new or old Aragorn would also make an awesome hero for a Gondor deck because he already has dunedain and old Aragorn has noble which combos with some new cards and you can put Steward of Gondor on him and give him the Gondor trait!