Yeah... I'd have to go with Malboros out of the options, as well. With Tonberries, once you know what they're about, you know that anytime you run into one, you just have to bring the pain down upon them, and hope to hit them hard enough before they eventually hit you. It's usually a 50/50 chance they'll end up killing a character, but that's about it. A phoenix down once its over and you're good
Malboros are different. You can be aware of them. But if you don't have a ribbon, and a lot of luck, running into one is still terrible. I think it's more telling that an enemy's reputation is enough to make you want to avoid them, and regret whenever you run into one unprepared