Got the NX30 - Which Portrait lens to complete the Kit Lens?

The kit lens is basically free, but pretty decent if you have a good copy. It actually stands up to 20 mp reasonably well.

Samsung native offerings for what you are looking for: 30mm f/2, 45mm f/1.8, 60mm f/2.8 macro, 85mm f/1.4.

The 85mm f/1.4 is a beast, but a beauty as well. It has wonderful image quality even respectable at f/1.4. It isn't very good at minimum focus distance, but even by typical portrait ranges it is great.

The 30mm f/2 is close enough to a 35mm f/1.8 that you probably won't notice much difference. Same with the 45mm f/1.8 vs a 50mm f/1.8.

The 45mm f/1.8 and 60mm f/2.8 are very similar for depth of field wide open. The 60mm has tighter field of view. The lens that stands out for shallow depth of field is the 85mm.

Of the 30, 45, 60, and 85mm, focus speed from fastest to slowest is 45mm, 30mm, 60mm, 85mm, with the 45mm really standing out. It is amazingly fast focusing (at least as fast as an SLR with a 50mm f/1.8 lens). The 30mm is fine focusing speed, and the 60 and 85mm are the only offering true manual focus (not focus by wire) which slows them down a bit. They are generally fast at refocus in good light, only problem if they decide to hunt.

I recently took photos of most of the lenses mounted on the NX30: http://www.dpreview.com/forums/post/53175890

To me, the 45mm f/1.8 is a must have because of its fairly shallow depth of field and near instant focus speed.  The 30mm f/2 since it is the sharpest NX lens, across the frame sharp at f/5.6 even on 20 MP sensor, this lens could handle even higher res sensor with ease, and the 85mm f/1.4 is special.  It won't appeal to everyone though, only get that if you know you need thin depth of field.  It is also very good for a general telephoto.  I use it at zoos, etc.

Eric