I have been playing primarily with a Leadership deck. It is comprised of the following cards:
According to a statistical breakdown the Leadership sphere has a good balance of everything. So onward I go with this deck into the next adventure Journey Down the Anduin. I will let everyone know how it goes.
I then read the following advice and may have to adjust my deck even further:
"The most broken cards in the core set are Steward of Gondor, Eowyn, Sneak Attack (w/ Gandalf), Test of Will and Northern Tracker, so just use those cards. Fill up the rest of the deck with cheap allies and the best of what's left, and choose heroes with the lowest starting threat you can possibly muster. Beating Journey Down the Anduin should be pretty easy from there"