I saw someone else do this, so I thought I might as well do my own take on it as someone with a fairly low voice (like, man low).

Sokkuri-san: Don't even joke lad. I almost passed out trying to sing the chorus of this song. WAY too high.

Kimi to XXXX Shitai Dake: The chorus is AWFUL. "Jigoku ni kimi wo otosu you" gets an honourable mention here too. I'd argue the chorus is easier than that specific line. The rest of the song is pretty fun to sing though, so I think I exaggerated a bit here.

Noah: Only that difficult cause I don't know the words and it's INSANELY fast. Pretty high too, but don't quote me on that.

Otomodachi: I have an awful time singing this song, but I don't think it's too bad once you get the hang of it?

Bot Bakka: I put this a tier too low. Fuck Bot Bakka. That's all I have to say for that one.

Hanabami: I swear, I thought this would be way harder. It's really not that difficult. Definitely easier than it sounds, still pretty hard though.

Suki, Kirai: Little bit too high for me, but it's easy enough.

Hanagatami: As the tier suggests, it's pretty easy if you sing it in head voice. It's a song that sounds best with that kind of tone, anyway. And it's one of my favourites. It's also easier an octave down, but it'd definitely be hard for the average female voice to do that. I just trained my voice to be masculine.

Devilish Girl: Same as Hanagatami.

Zoku Zoku: I haven't sung it, but just by listening I feel as though it's probably the easiest on the list if you know the words. I probably won't ever sing it, since it's my least favourite PS song (sorry Zoku Zoku fans, it just isn't for me).

Otomeshinjuu: My only issue with this one is that I don't know the words well so I stammer a lot while trying to sing it. Swing rhythm gives it extra points for difficulty, but other than that it's definitely easy.

How easy I think Phantom Siita songs are to sing (with explanations)