Crusade rulebook

I wanted to ask which 40k crusade rulebook is the most recent one? The Armageddon or the nachmund gauntlet?

My friend and I wanted to start a narrative story and never have played a crusade before. I'm a noob/ mediocre player with about 20 games experience and my buddy has just started playing 40k. However, we would like to to try starting a crusade so my question is: is a crusade easy to play/understand if one understand the basic 2000points game? Is one of the books easier to understand/play?

Thanks in advance!