With Lundqvist, it's pretty much a story of what you see is what you get at this point. He's already a very accomplished goalie who relies on his brains and positioning more than his excelent physical talent to make his saves. He also has great reflexes and extremely quick legs that allow him to make close-in saves that most other goalies would not be ashamed to miss. Although you could say that he doesn't have much improvement left in him, you just have to look at what he has acheived over the last few years to see that he doesn't need to improve much more, either.
Toivonen is younger and probably does have more room to grow. He's got incredible athletic ability and good brains. But if the question is does he have the kind of vision that Lundqvist does? Lundqvist's positioning is almost always spot-on, whereas Hannu has the flexibility and speed to catch up when his isn't. Toivonen is a much more spectacular player, and will probably be near-unbeatable at times in his career, but with all young players who still need a little more experience, the question is open as to how far he can go to reach his potential.
Miller, I don't know too much about, except that I think that he is very, very solid and will continue to quietly get better. He really needs more muscle, though, to have a good long career.
As for Niittymäki, even though I'm a TPS fan, I have always thought that he looks too small in net. I never like goalies who sit back in the goal. I never thought he looked like a top starter. But he never stops proving me wrong. I don't think he'll ever win a Vezina, but worse, as a Rangers fan, he looks like a money goaltender who wins playoff series.
