Spritech bar end works well for me on drop bars. I like that it stays in place and does not need constant adjustments.
I have yet to find a mirror I like for upright bars. They all either stick out too far or need adjusting because the get in the way of hand positions.
__________________
84 Bridgestone 400. 90's Basso Highway, 07 Rivendell AHH, 16 Clockwork All-Rounder , 22 Rivendell Roadini