I prefer Jill in the original because her storyline is better, the lockpick is more useful than the Lighter and having 6 item slots is just way to annoying. For me that doesn't add to the challenge, it just makes it more annoying. Jill's game is slightly easier but overall I just like Jill way more than Chris.
Who said anything about Chris' game being tougher? In some aspects its easier. Flash grenades make it easier to take down enemies. He is physically superior to Jill in that he can headshot better, and he moves faster. Old keys are hardly an issue since the respective door is usually just a stone's throw away. His inventory slot is the only real problem. But good item managment and me knowing the game like the back of my hand alleviates this problem. I personally like Chris' game because his game feels more survival horror to me. As in, he's by himself way more (Jill gets way too much help from Barry).
As far as story goes, Jill's game is definitely better in that regard, but only because of Barry. She is just as flat and uninteresting as Chris is in her game. I still find it interesting that both side characters are more interesting than the actual character you are playing as.