I really enjoyed Festival of Blood as well, and I keep meaning to go back and replay it around Halloween time. But then I forget amid all my backlog. Maybe this year.
Not having played Second Son, I like inFamous 2 the best, then FoB, and inFamous 1 last--though I wasn't disappointed about it in any way since I got it for free in the Welcome Back games and found it to be a really good, though not great, game. True story, I bought inFamous 2 for $24 as part of a specially advertised bundle sale for Plus members two days before Sony launched the IGC, which included inFamous 2 free for Plus members.
But like king3pj said, 2 improved upon 1 in every conceivable way, and I don't regret paying for it along with all the worthless DLC skins and weapons that were part of my bundle deal.