I think that the X-ring is better, it was made for dirt really.....
as for the best etc. manufacturers make about 4 choices ususally and the top one is always the 'bling' model with anodised gold sideplates so you can avoid this one.
several people go by the breaking strain but i found that a poor indicator of durability.
I used Iris a lot based on this and liked them and sold them as well.
the trouble is, if you try them in winter they wreck easily. if you go through a river, that wrecks them, if you ride sand all day, that wrecks them.
if i lived in a dry desert I could do you a comparison.....
Taffy