have admissions into Grinnell, Trinity and University of richmond--- what is guidance to select one

It looks like you are an international student.

If you are an international student, the two things that matter are:

  1. which of these places employers in your own country prefer - you will need to plan on getting a job there after you finish your education in the US and any work here that you were able to do with OPT
  2. which of these places has decent job placement for students with OPT

Ask the international students office and the career center at each of these colleges/universities about OPT placement. If they can’t give you solid information about their track record for that, then you know you will need to plan to leave the US very shortly after you graduate.