Devil Survivor is bullshit in difficulty terms. I had to cheat to beat Beldr (honestly, this guy defines "unfair") and everything from 6th day evening is a big "Screw you!" in my eyes. Rest was nice, yeah, but I just couldn't bother to finish this game.
Strange Journey is SO MUCH easier IMO. It's still challenging for sure, but if I need to, I can at least go and gain a few levels and get myself a few more demons for fusions. In Devil Survivor? If you got the wrong demons, have fun grinding the hell out of the optional stages for Macca. And if you got the wrong demons for those? Sucks to be you!