Also, tell me your reason. I think the Rat is better because he is more powerful and mature. While the Scorpion is hot headed, I am not saying he is a bad villain though. If Scorpion made more than 2 appearance, his character would have developed more and become a better villain
Well when you look at their overall power, they would be on equal levels, with Scorpion being more of a glass cannon and the Rat taking his time, being more methodical.
If you mean as villains in general, I would believe Rat to be more villainous because he put in more of a wise look into his plan vs Scorpion who, yes was smart in his way of going through the Djinni order to get the chronoshards, aside from that point didn't necessarily think his whole plan through, which is why pappy spider had to clean up his mess.