One Piece 696:
I recognize it's not fair to compare the two of them power wise, but in the world of One Piece this doesn't matter when considering their end goals. Chopper wants to be the best/most dependable doctor. It doesn't matter what power his rivals/opponents have, that's his goal, similar to Luffy wanting to be the Pirate King/Zoro wanting to be the best swordsman etc. Remember when Zoro had to fight Mr. 2 with his ability to turn his body into metal? Was it fair to compare the two of their abilities? Yet Zoro overcame that. Chopper "should" be able to become a better doctor than Law at some point, if Oda still plans on keeping that theme in tact (who knows, maybe Law will stay better than Chopper in this area because of his powers?). Regardless as a reader of One Piece, Law curing the kids and Chopper running around screaming "Murderer" made Chopper look helpless in his strongest area. If Oda wanted to, he could have had Law not worry about the kids and let Chopper cure them somehow but I "think" Oda did that on purpose to give Chopper something to overcome, but we'll see.
This is where I disagree. Maybe not YET in terms of where the story is now, but by the end of One Piece, Chopper should be able to handle any situation as a doctor of the Straw Hat crew or he will have failed his goal IMO. Law, Ivankov can still be rivals in that regard, but Chopper should have his own way of handling any "doctor problem", with or without their Devil Fruit abilities.