even if I am crazy about the 5164A, I have to admit that now, I would have some hesitations if I had to choose between those two.
5164A has the GMT function which I consider as very handy.
5168A has a bigger diameter which could fit better on my wrist; I also like its fun colors. The chrono is cool, especially as it is a flyback, but I am not sure about its utility for me; I had a chrono before but I had never really used it... except for my pastas. ;-)
Best
Rod
PS: thank you very Magnus for your nice pictures