Kuiu - I have the 120 crew, LS crew and hoody - thicker, more comfortable, no zippers, less bulk due to lack of zippers and no chest pocket.
Sitka - I have the 120 crew and the 120 hoody - thinner (very thin), half zip on hoodie with chest pocket that I never use. I havent had durability issues with the hoody, but I cant stress enough how thin it is. I have had some widening of the neck on the crew - of all these pieces, I probably wouldnt buy the sitka 120 crew again because I just cant see it lasting. Ive used the 120 hoody more than the core lightweight this year, and prefer it.
Id say if you plan on using the kuiu 120 hoody or the sitka 120 as an outer layer more often, get the sitka. If you are going to use them more as a base layer, the kuiu is a bit warmer and more comfortable. The loftier Kuiu would snag more, the Sitka 120 is tigher woven and would hold up better as an outer layer.
To me I think of the 120LT as base layers that I layer over and dont wear much as an outer layer. Ill usually wear the 120LT crew under the core lightweight/sitka 120/core heavyweight/midweight etc. Ill use the 120LT hoody or crew as a baselayer under the ambient hoody or apex, etc. I only have the kuiu in solid colors, and end up wearing them as a base layer around town or at work. Really comfortable pieces.
Out of the crew options, Id take the Kuiu all day every day in any situation.