Choosing an apt font for the texts of your presentation-slides is a significant decision as far as the extent of impact is concerned. Carving a good content in a PPT is important, but selection of an appropriate font to wrap that content is equally important, if not more. People get reluctant to use normally used fonts because they want their presentations to appear unique and special. But that should not be the criterion; the only criterion should be the legibility of the texts and overall impact of the presentation.
You must also bear the occasion or the ambiance of the impending presentation in your mind while selecting the font for it. In a quintessential corporate ambiance, where a presenter carries through the presentation, you can opt for a stylish but less emphatic font, whereas in a conference, where the presentation itself is the sole communicator, you can opt for an emphatic font. In a one-on-one presentation, legibility becomes the only criterion. Normally, traditionally used fonts like Arial, Rockwell, Times New Roman (for Titles) or Calibri are always handy to use. These are customary fonts on every computer, so you know that your presentation will appear before your client in the way you have prepared it. And that is the real relief.
All-in-all, a font is to highlight the texts you have presented which bear the real message for your client. So, the font in your presentation has to be selected in view of the impact of the entire presentation.