I have to agree, the Nemesis Elite has the best stock cooling I've seen on a case (3 120mm, aluminum), but the case itself looks a bit immature, even for my age (15yrs). But if you can get premodded cases, a Lian-Li P-series with an extra blowhole will do a great job.
But if you want the best cooling, you'll need a higher cap. I'm spending 300 bucks on a Lian-Li V1000B with a bunch of mods including an extra 120mm blowhole. I hear this is one of the best air-cooled mid-tower cases you can get, and a plain V1000 with no mods or windows costs about 190.