My instincts aren't perfect, but I'd -avoid- a sensor-controlled fan for -intake- air: that fan's sensor should -always- say "intake air's cool, I'll just idle away at low speed". Save sensor-equipped fans for -output- use; better yet, skip the issue by running a quiet fan at full speed as this may cool down hotspots elsewhere in the chassis by increasing overall airflow.
(Ideally, both intake and exhaust fans would have -remote- temp' sensors for measuring it where it counts, not where the fan blades are, right?)
I'm a big fan of GiZzO's page , yet I'll disagree with his/her/its recommendation, above, and rashly declare getting a Papst doesn't seem worth the effort/$ unless you're in Europe where they're cheaper and more available. I'm leaning towards a Panaflow in the purchase I'm about to make.