Which part of human body sustains most pressure when standing up straight?
It is logically clear that the ankle could only partly be analyzed in the group of joints that are below its height. There is no direct way to measure the pressure on ankle joint (on talus bone), but from the logic it is clear that it should be the point of highest pressure in the group of points lister in the question, however the pressure is distributed through the other joints of the foot. 

Below are the graphs of pressure distribution according to surfaces (not joints). From the graph we can conclude that part of the pressure experienced by ankle joint distributed tangentially to metatarsal region and other surfaces.



Indeed the highest pressure in standing person in on feets. The term you are asking about is foot pressure distribution (FPD).

In we assess the FPD dynamically, in younger persons the FPD is nearly equivalent between calcaneus region and metatarsal region, while in older persons the FDT in calcaneus region is higher than metatarsal pressure.

During stance:


Foot pressure distribution. A. Maximum pressure distribution on all sensors during stance for one subject. B. The nine anatomical masks superimposed on the insole (MC = medial calcaneus, LC = lateral calcaneus, MA = medial arch, LA = lateral arch, MT1 = first metatarse, 3 = second and third metatarse, 4 = fourth and fifth metatarse, H = hallux, and T = toes).



Pressure distribution by anatomical region. Normalized maximum pressure distribution for the young (white bar) and elderly (black bar) group for each anatomical region (medial calcalneus mask p = 0.0001, lateral calcaneus mask p = 0.03):



source article, you can find much more using FPD as a keyword.