kkards, I've got that Gap tee. It's great!
Tracey's, I agree with the critical dip of the v-neck. Being busty means I need to be very careful! Even the bra I wear with certain necklines can change the appropriateness!
Peri, I will definitely share on the see-through front. I love thinner fabrics for the coolness and drape but the trade off in the lighter colours is transparency. Is the only solution to wear darker colours?
I actually like all four but am leaning towards Everlane because they are cheaper. I don't like to spend lots on a white tee because they only last a season +. But I also want to spend if it's going to make a difference. A great white tee would be a workhorse for me and I'd definitely duplicate!