The best dSLR you can buy is the latest model. The best value is last year or so's model at a massive discount . If you like Nikons (and I do even though I currently use a Canon) the D5100 is being cleared out at really good prices. Great low light performance there.
There is no such thing as a good on board flash (except the Fuji X100) but, from experience, I'd say Nikon do better flash metering than Canon for instant gratification.

Also, camera bodies are transient while good lenses will last for years. Look into the lenses you need before committing to a system.

PS: you didn't process your own Tri-x?