Couldn't disagree more! I think you just havent had a chance to watch him enough. Cruden is a fantastic player, IMO on the verge of becoming the AB #1.
You say you want to look at test match rugby only, which for a start is a strange thing to do given the majority of the rugby we have seen both men play is at Super Rugby level, and particularly because Barrett has had such limited international game time, how many games has Barrett started? 1 game is it against Italy?? and the rest of the bench? Maybe he has started 2, I can't recall though.
But lets go with your selective analysis; Cruden has been given the opportunities at 10 plain and simply because he is a better option than Barrett, a significantly superior player. I think what happens is that some marginal fans flick on the TV and see a player do a couple good runs and get convinced he is the next big thing, and forget that rugby is much more than running the ball. Don't get me wrong Barrett is a good player and may even surpass Cruden eventually (I doubt it though), he will certainly be a great backup and bench option as he can cover 15 as well.
Did you watch game one of the RC in Sydney? Cruden was very good in that game - far more impressive than Barrett against a 14 man SA squad at home in NZ. I would also urge you to look at the last couple years of Super Rugby as well. Cruden has been masterful two years in a row leading his team to two championships. Barrett had a good year in 2012, and was OK this year, but he has significant deficiencies in D, his all round kicking game needs work and his goal kicking is average. Cruden on the other hand is the whole package now.
No doubt in my mind who the next #1 10 is in NZ