Schumacher never felt threatened performance wise by a team mate. Alonso has, and when he does, tends towards the dramatic. In the case of both Alonso and Vettel, we see them lash out; in Vettel's case revealing a vengeful, wild nature. In Alonso, someone who is probably never wrong.
I think Hamilton is probably the fastest, most skillful maybe of all time. BUt Schumacher is still the best *racing* driver, because part of his feature set is that he was always cool, calm and collected. You saw looks of grim determination from him, but not pouty and surly. He got frustrated, but he didn't turn that into something directed away from himself.
Compare Schumacher's attitude regarding Nico's performance against him, and Alonso regarding Felipe or Hamilton. Compare on occasion when Rubens got the best of him, and Schumacher's pleasant smiling "go team" demeanor. He may have hated it, but *he was in control of himself*. It's what gave him the edge. Even when he was angry at Coulthard at Spa - he was quite business-like in his "fury".
Seeing Alonso's tantrums at McLaren, reactions to Trulli, and today - he's not Schumacher. Vettel's vicious "get him out of the way!" when he wasn't close to Webber, and the psychopathic attempt to conceal in front of the world - not becoming of a champion, IMO.
Schumacher was the most complete driver we've seen, Alonso is great but he has flaws. Lewis has the onus of wanting to make up for that first season that could have been; he can't be perfect, but managing a human standard for himself seems to be a weakness? Kimi's strength, that probably has an impact on the whole field today, is that he has that Schumacher air of not being fazed too much. If he's having a technical problem, you know his personal performance is probably not being impacted by it. Schumacher's blank poker face - not the most endearing trait as a person, but as a racing driver a potent ingredient.