Note: not asking about length or colour; just shape.
Most Helpful Guy
Pointy or Ballerina. Preferably the latter. It's got some of all of them there. Plus nails like those feel damn good digging into my back...
Most Helpful Girl
I am a fan of the square nail shape. It seems like the most comfortable shape, to me. The square shape suits me when I have baby pink as my nail polish color. Along with the round shape, the square shape may look presentable even when one's nails are trimmed short.
The only downside I see in shaping my nails in squares is inconvenience when doing my solves in Rubik's cubes. There was a time when my manicure almost got ruined because of executing a tedious algorithm in an utterly swift manner. My nails were trimmed squares at that time and they were quite long to the point when one fingernail actually got chipped slightly.