While NTFS works, FAT32 is the most compatible format for both Wii and GameCube (Nintendont) homebrew.
If you’re on macOS, Witgui is a clean, graphical interface for "wit" (Wii Intelligent Toolset). It allows for easy conversion and renaming of game files to ensure your library looks organized. Best Practices for Your Wii Library
The Ultimate Guide to WBFS Files and Wii Repacks: Save Space and Simplify Your Library
You can fit 3–4 times as many games on a 128GB flash drive compared to using raw ISOs.