Should we change wireless protocol in our office? We have A, most new laptops don't read A.

I have wireless A in our medical office. Need new laptops, most don’t read A. Should we change? To G? To N? Most of what we do is internet-based, no need for high-power video or graphics. One of our tech consultants suggests we stay with A, but this doesn’t seem quite right given where the field is heading. Thanks!