Modding a Nintendo 3DS XL requires a microSD card to store custom firmware and other files. The best microSD card for this purpose will vary depending on the specific model of 3DS XL and the desired performance. However, some general tips can help you choose the right card.
First, consider the size of the card. A larger card will provide more storage space for games, apps, and other files. However, it is important to note that the 3DS XL only supports microSD cards up to 32GB. If you need more storage space, you can use a USB flash drive or an external hard drive.