The best size for a travel journal ultimately depends on individual preferences and needs. Some travelers may prefer a compact and portable size that easily fits in a pocket or small bag, allowing for on-the-go journaling. Others may opt for a larger size that offers more space for writing, sketching, and attaching photographs or souvenirs. A medium-sized journal strikes a balance between portability and ample writing space. Ultimately, the best size for a travel journal is one that feels comfortable to carry, provides enough room for creativity and organization, and suits the individual's writing and artistic style.