I have heard good stories about tri blends. search for a thread that talked about AA closing/file for bankruptcy. It's discussed there. I have had bad experiences with 100% cotton ones. Stay TTS. You don't want to throw them in the dryer. The shape changes dramatically.
They are not at that level, trust me. The viscose Ts are good for layering, but theres a limited color choice. For one they don't have the length of RO ones, and the material isn't as nice when put on. Plus, you get more nipple gating from the viscose ones on its own. Of course this all depends on which Ts you were referring to.
Don't like the nipple gating part. The main reason that I like the RO tees besides it's length/raw hem, is its material. Mine are either rayon/silk or cotton/silk, so comfortable. At the same time, 100 for a tee is