Choosing a wide angle lens

I posted in the Nikon lens section but am asking here as well with more specific attention given to astrophotography.

I'm torn between the Nikon 16-35 f/4 and Tokina 16-28 f/2.8 as my wide angle lens on a D600. I'll use it for more than just Astrophotography but with respect to it how would you choose? Would getting a low cost manual focus Samyang 14mm for just this be a better option?