Which two of the three DLC Packs is the best for ME3 is the best?

[S.T.A.G.E.]

I got from Ashes already, I am just trying to figure out which DLC to get and Citadel seems like the best DLC from what I am hearing, but theres also Leviathan and Omega. What do you think? I've added a poll to adjust to what everyone has said and keep it accurate. If you have length of play and spoiler free info and reasoning as to why any specific game is worth the price let me know. :)

 

Thanks guys!