But we dont know did Nagato got sick from Rinegan or when he fought Salamander but there must be a reason why he is afraid of sharingan user Madara so i think the best doujutsu is in the person using itman the rinnegan is the best of them all (well my fav is sharingan but still).
why?
its ability's:
sense chakra like sharingan and byakugan
can use 5 elements + gravity(pretty cool)
and said to be able to use all jutsu
ithink that is enoth and i douth that sharingan can copy
Banshō Ten'in
Chibaku Tensei
Shinra Tensei
and the 6 vody thing is lil bad since it must be really irratating to have to use them but there good thougth i would prefer if could use all there power's in is owen body