Late Goodbye, Roses, Maybe Tomorrow is a better day, just basically any soft song from Poets of the Fall I like.
Hands Held High is a song by Linkin Park that gets me just about every time, it's a beautiful song.
Other songs are
The Diary of Jane (Acoustic) - Breaking Benjamin
Not Good Enough for Truth in Cliche - Escape the Fate
The Bleeding (acoustic and regular)- Five Finger Death Punch
The Approaching Curve - Rise Against
And this song isn't actually sad but it's a soft song that I like very much, it's called Goodnight Demonslayer by Voltaire