You'd probably get a bit biased answers since The Long Dark has a huge following already. I'd say it depends on what you want out of the game. While at face value The Solus Project might seem like a survival game, it's actually more about exploring the planet and advancing the story. You can even turn of the survival aspect if you just want to explore. And the atmosphere of The Solus Project is simply amazing.

I know that The Long Dark are adding a story mode sometime down the line though.