10MP: plenty for viewing on phones and computers and for social media. Small, easy-to-manage files - great if you mostly shoot for the record.
24MP: comfortably supports A4-A3 prints and is the best-balanced choice. When in doubt, pick this.
60MP: maximum quality for large prints, aggressive cropping, or archival purposes - it records the film grain itself. Especially worthwhile for 120 (medium format), which holds more detail than 135 to begin with.
One caveat: higher scan resolution cannot invent detail that was never captured on the film. Work backwards from how you plan to use the images.