I've gone mostly to DIY power cords which are quite unwieldy but, back in the day, I found the offerings from Wolff and 6Sons Audio to be both very good and quite flexible. 6Sons Audio Golden Eagle is the best power cord I've heard. Neither come up very often but usually are a bargain at used prices.
Do good power cords have to be stiff?
As far as I am concerned, stiff power cables are a pain in the butt. Wonder if anyone has found a great power cable that is very flexible?