So what's up with "single origin" chocolates that you hear about once in a while?
Different soil compositions is the main reason why beans from different countries/regions/plantations can taste very different, or have different flavor notes. This is also why single origin, meaning that the beans used in that chocolate are all from the same region (usually country) chocolates have become popular. Single plantation, are a type of single origin chocolate where all the beans have actually come from just one plantation. They allow you to really understand the beans (and thus the soil tendencies) of that area.
On the other hand, blended chocolates are usually more balanced, and often have more flavor notes, with each flavor more pronounced than the flavor notes of single origin chocolates.
So which is better?
Depends on what you like.
I like both.
Single origin chocolates can be really great if the beans are really high quality and the resulting chocolate has been carefully blended and crafted within the confines of a region so that one flavor note isn't overpowering. I also think that they are great when making hot chocolate. It gives you more control over the resulting flavor of your beverage.
Blended chocolates are more of a guarantee that the overall flavor will be balanced.