MoF is definitely the easiest for me in Normal Mode. Bombing has always been the very first survival crutch for many players so when a game drip feeds you bombs every couple of seconds AND the build of the scoring system is partly based on bombing incoming bullets, the entire thing becomes a regular activity rather than a spontaneous split second decision between survival and stock reservation.
To its credit though, the bullet patterns are actually pretty difficult and complex on their own so keeping yourself from bombing every other moment is already enough to slightly amp up the challenge. Also, there's a really sudden rise in difficulty curve when Kanako appears (not counting that BS Aya). Bullets are insanely fast and the pattern-based ones are actually pretty hard to figure out on the first try. Most of her attacks are pattern-based though so simple memorization is mostly enough to beat this boss(not counting the final spell card).
I think almost everyone already said this but SA is definitely the hardest on Normal Difficulty (possibly on others as well). When a ton of crap are already flying at you
on the very first stage, you know you're in for a world of hurt.
This game is heaven for graze-happy individuals and hell for everyone else.
EoSD is second hardest for me and there's a slight tie between PCB and IN. I found IN to be a bit easier than PCB though. I'm not sure about everyone else but I found IN's controls to be a bit smoother than PCB and that helped me quite a bit during the game.
You only get many extra lives in sa if you cap spellcards.. if you bomb them, you get squat.
correction:
Even bombing a spellcard will still give you that star fragment. It's a sort of an incentive to encourage players to use bombs often....or rather, enoucarage players to not die needlessly.
IMO though, it's still easier to gain lives in any other game than SA. Scoring in a game almost completely coexists with simply playing the game so you can always gain lives at any given time. Even PCB and IN is easier because all you need to do is to take advantage of the POC which is a rather easy thing to do in those games. In SA however, you are required to do a specific task at very specific points in the game so every screw up is a life fragment lost. To add insult to injury, screwing up means you just died so when you add that one up, every failure takes from you 1 1/5th of your overall lives. That's definitely a worse punishment than any other game. Considering the difficulty of this game, this lives system just adds to the frustration.