Really? Can you give any specific reasons why? Because I happen to be having trouble deciding which one to download right now.
Well, I'll preface my reasons by saying that I am pretty big fan of post-apocalyptic stuff, love the setting. I am Alive also gives you a lot of bang for your buck (one run will take you at least 5 hours), creates a great feeling of tension (in the combat, the climbing and the exploration) but doesn't do it with overly hard or cheap gameplay. You need to think about how you are going to handle combat, plan out your routes when climbing and look out for trouble when exploring. They really nailed the atmosphere but not at the expense of fun imo.
There is definitely some jank with the game though. Mostly with the controls which can be a bit finicky here and there but it never bothered me to the point that I felt like griping about it.
Journey on the other hand is almost the exact opposite. It's very short (and imo not something I'm motivated to replay) and very reliant on it's artistic value and the player's willingness to let the story suck them in. Where I am Alive drew me into it's world by doing so many things to make me feel like I was actually living in a post-apocalyptic world Journey was too nebulous and vague for me. It is a great game and I enjoyed my playthrough but it was too dreamy and fluffy for me, I finished the game feeling that beyond the experience there wasn't much there for me to hold on to.