Personally, I use Paul Buff "White Lighting" units, three of them. The lights are bounced into white umbrellas. If I were buying new, I would but softboxes for the lights instead of umbrellas.
It's hard to pick one thing: the sensor cleaner is a big plus. Even though I don't use it alot, I really like LiveView. It comes in handy when shooting macro stuff close to the ground.
I've been using Nikon gear for many years. I've been digital since the D100 came out. I haven't thought about film since then. I do alot of nature and sports photography, along with some forensic photography.
Gear
D100, D200, D300 , D2H and several Nikon lenses.
Gitzo tripods and monopod, Arca Swiss and Kirk ball heads.