The best way would be a XML. You can make many other things with it.
The cool thing is:
You create the way it's organized, not limited by groups like in INI
For example, I'm developing an rpg system which has its characters set by an external file.
And I also have a second one just with the text.
Dialog example(which can be furter developed, you can nest an infinity of text inside each character for example)
<character-a>Grab your destiny!</character-a>
<character-b>Did you see the ghost?</character-b>
<character-a>The cake was a lie.</character-a>
<character-b>There was no ghost? Myths are created by a lack of purpose.</character-b>
Example of data for a character, which will get interpreted during the excecution, I can't stop to think about the creative possibilities brought thanks to it and the modularity we could achieve, like, an editor with really easy and straightforward sintax:
<monster name="Pikatchoo" type="famous" atk="12" def="12">
<info>It's a clone of a famous japanese character, always with the flu</info></monster>[/code:6zm3cgim]
Here is a tutorial link which explains how to get the values from a file:
I suggets also taking a look at w3schools, I found their explanation really easy to grasp and in 3 minutes I was making a heavy-nested file filled with data for characters.