Messi is a great player no doubt. When people ask me who I think is best out of Ronaldo or Messi, I tend to say Ronaldo though. Sure I know Messi has great statistics in the El Classico-games, and I don't mean it as anything negative towards Messi, but in terms of being a more "allround" player, I think Ronaldo has that. I mean, he started out as a sort of Right Midfielder in Man United (in a 4-4-2 system), but eventually developed his offensive game loads, becoming more of a winger, and also a striker. I think Ronaldo has a few qualities that Messi doesn't have, like being pretty good on the head, great corners for example. Messi might be more technical, so this is just how I feel "overall".
Honestly I don't really like the term "best player", because it is impossible to judge such a thing. The general idea is that people go for offensive qualities such as goal-scoring, technical abilities, but Defensive ones are just as important in the sport.
Personally I prefer the term "Favorite"-player, because it's a subjective thing after all. And on that part I would say Özil, who scores goals, but also makes incredible assists. Seeing him in the World Cup '10 was amazing, and he did a big impact on me personally. I think he could take another step and become even more awesome, but he's one of the best playmakers already, and I'm still really bummed that Man U didn't buy him when they had the chance, he joined Madrid for like 8 million € or something, real bargain.