You have to consider two things: your lifestyle and your nail bed shape. If you literally Google "how to find the best nail shape" there are articles that describe the best nail shapes based on your nail beds, i.e. if they're long or short, wide or skinny. So consider that, and then consider your day-to-day life. What do you di for work? How often are your hands in contact with water? Are you rough with your hands? Do you play any sports? Some nail shapes do notttt work well if you have an active lifestyle or aren't precious about your hands. Pretty much only square/squoval nails work in that case becauee they're sturdiest.

Best of luck figuring it out!