Well, the two fan controllers I'd be looking at would be a Scythe Kaze Meter or a Sunbeamtech Rheobus Extreme.
Scythe Kaze Meter:
Pros:
Looks awesome
Displays the fan speeds
Handles 4 fans
Cons:
Expensive
Controls only 4 fans
Sunbeamtech Rheobus Extreme:
Pros:
Controls 6 fans
Very affordable
Up to 30 watts per channel
Cons:
No display
Doesn't look all that fancy
BTW: Nice system specs.