What's the toughest song you can sing decently?

I've been contemplating trying to sing some more difficult songs (like unchained melody, bohemian rhapsody, take on me, ect) and it got me thinking about which songs I currently can sing that I would consider difficult to perform. Now I'm curious about everyone else too. What's your toughest song?
Currently the toughest song I can perform decently is "All of Me " by John Legend.
Currently the toughest song I can perform decently is "All of Me " by John Legend.
Comments
Take on Me by A-Ha
Sherry or Rag Doll by Franki Valli
I have a pretty good falsetto lol
What -I- find hard that I think do ok:
Sister Christian by Night Ranger
Modern Love by David Bowie
I would say The Show Must Go On? Definitely one of the harder ones.
Livin' On A Prayer (Only sometimes) - Bon Jovi)
Holy Diver (Dio)
A lot of Freddie songs honestly. They're almost all challenging.