Like everyone said, I went with the white ring sight, but the USSS sight would also be a great choice (Nether requires any batteries to work) and you can still add a aftermarket if wanted.
I also would like to aquire a USSS sight but not at the current prices that are being sought which are 1/2 the price of entire weapon system. I could see if the USSS sight had a built in digital readout rangefinder to ask that much, but at the prices people are asking its ridiculous.