Transparent and white backgrounds are both useful, but they solve different problems. Choosing the right one depends on where the image will appear.
Transparent Background
A transparent background is best when the image needs to be placed on different designs. Logos, stickers, product cutouts, and profile graphics often work well as transparent PNG files.
White Background
A white background is common for ecommerce listings, documents, thumbnails, and clean product galleries. It looks consistent and is usually easier to export as a smaller JPG file.
Brand Color Background
Sometimes a brand color is better than white. A soft brand background can make social media graphics and promotional banners more recognizable. Make sure the subject still has enough contrast.
Practical Rule
Use transparent PNG when you will reuse the subject in many places. Use white or solid color when the final image has one fixed purpose.
Conclusion
There is no single best background for every image. Think about the final use first, then choose transparent, white, or color based on clarity and consistency.