Sigma 30mm 1.4 VS Nikkor 35mm 1.8?

I want an everyday lens, from landscape to portraits. I have the 50mm 1.8D but it does not autofocus on my camera. Also, the more bokeh, the better.

Those lenses would still be too wide for most landscape applications, and too short for portraits.

Meanwhile there isa 50mm/1.8G that would autofocus on your camera, and of course the brilliant 50mm/1.4G.

As a lens that is suitable for both applications, consider a 17-50mm/2.8 lens. Nikon makes a hideously expensive one (17-55mm/2.8), and there's a very popular one by Tamron, either with or without image stabilization.

If those lenses are attached to a Nikon APS-C sensored camera, they will not be wide enough to shoot landscapes ( you need something like a 12-24 mm for that)

Link to a typical landscape using a 12-24 mm lens

You have the right focal length in the 50 mm for shooting portraits (medium telephoto).

What is important since you want auto-focusing, is that you buy only AF-S lenses for your entry level Nikon dSLR

The longer the lens, the better the out of focus area behind the subject when shooting using selective focus. Those two "normal" lenses will allow less selective focus when compared to a longer lens like a 85 mm for instance

Here is how some lens designs effect what you like to call Bokeh

http://www.kenrockwell.com/...arison.htm