Many factors apart from area. Windows facing west? How's your sensitivity totemperature (e.g. some people put on coat in bus during summer)? Location of the
AC indoor unit (facing you?)?....
If I were you, 3HP is the minimum. 3.5HP is better.
Always remember: don't let the AC always work at 100% e.g. small AC installed in large area.
Daikin is the best if you can afford. It offers some hi-end series.