Panty and Stocking are the main ones. Writers like to take these two characters and put them in different scenarios. They might change their personalities a bit, but still keep their core identities. Fans are interested in seeing how they react in new situations, whether it's a different kind of battle or a strange encounter with a new character.
One common theme might be adventure, as the original characters are often in action - packed situations. Another could be friendship, showing how the characters interact and support each other.
One interesting aspect could be the unique character interactions. It might explore different relationships between the characters in new and unexpected ways. For example, it could show how their personalities clash or complement each other in different scenarios.
Panty is definitely an interesting character to write about. Her brash and bold nature, along with her rather unique 'weapon' in the form of her panties, can lead to some really out - there story ideas. For example, a fanfic could explore how she came to be so confident and unashamed of her abilities.
One popular theme could be alternative adventures for the main characters. For example, they might go on a different kind of mission in the strange world they inhabit. Another theme could be character relationships explored in more depth, like how Panty and Stocking interact with other supporting characters in ways not shown in the original work. And sometimes, there are themes related to power -ups or new abilities that the characters gain.
I'm not sure about a specific 'Panty and Stocking with Garterbelt' fanfic that stands out above all others. However, you could try checking out some of the more popular fanfic communities on Reddit. There, fans often share and discuss their favorite fanfics. You might find one that really catches your eye, perhaps one that has a really creative take on the characters or the world they live in.
One common theme could be the exploration of the unique relationship between Panty and Stocking. Since they have such distinct personalities in the original work, fanfic might delve deeper into how they interact and support or oppose each other.
I'm not sure if there are many good ones. It's a rather unusual crossover. However, you could start by checking some popular fanfic websites like Archive of Our Own. They might have a few, but it could be a niche area within the fanfic community.