I somehow missed this post, only saw it after clicking on the notification.
Anyway, the part about why I take part in these discussions, I already wrote in my previous post in this thread.
I can only say that for me Messi is the best player in the world because that's how I see it. I don't know if he's the greatest player of all time because I didn't see the other contenders play. And no, I don't consider Ronaldo a contender for the greatest player of all time, I just don't. Top 10? Absolutely. Top 5? Probably. Top 1 or 2? Not for me. He's a phenomenal player, though. I just look for something different, something more in a player.
Regarding Juventus, they would have been out of the Champions League easily had it not been for Ronaldo. In fact, I think they wouldn't even have had a shot at advancing without him. Not just for the goals, but his presence as well made them believe, I agree with this. Anyone who considers Ronaldo average is trolling.
Regarding the EURO, I think there is a difference between taking credit away from Ronaldo completely, and arguing that the tournament was won because of him. Both are wrong, IMO. It's the idea that somehow Portugal were spurred on by Ronaldo that I have a problem with, because I don't think he had or could have that effect. This is different to what happened with Juventus in the Champions League because he was on the pitch, he scored the goals and carried a very heavy burden to help his team qualify. In the EURO, he was injured. There's a difference, and the desire to elevate him goes so far that people suggest he was the reason they beat France, which is overdoing it IMO.
Regarding your last question, I would pick the player that I consider to be the best player I've ever seen. So, Messi. Why? Because his way of playing and his skillset mean he is going to carry the team regardless of what its weakness is.