Styx looks like a poor man's Assassin's Creed, but for free, I'm in ... if I ever get around to it. I heard the story isn't exactly compelling.
Mousecraft looks cool. I remember when it first came out saying to myself, "I bet this will be free for PS+ someday, and I'll play it then."
rain looks intriguing - a simple puzzle-adventure-platformer with a "gimmick" and emotional story similar to Papo & Yo, Contrast, and Brothers. I'm always up for that.
The others really aren't my cup of tea. Entwined looks beautiful, but I think the precision gameplay required to get all the trophies will have me tearing my hair out.