Sigma 50mm F1.4 EX DG HSM Vs. Nikon 50mm f/1.4G SIC SW - D40

Hello guys, I am planning on getting a 50mm lens for portraits and some street photography (something focused in foreground and background would be all blurred). I am looking for a solid IQ, nice difference b/w foreground and background, and nice bokeh effect. Price wise, they are almost the same. I was wondering which one should I go with.

I don't have much photography experience...I have nikon D40. I just want to get 35mm and 50mm lens. I think once I get 50mm, I will wait for a long time before I buy 35mm (by then, there will be 35mm F1.4 )

Thank you