I always encourage people to use plain fonts in their presentations. Curly (or serif) fonts are beautiful and I love them when they are used in the right place, for example for signage or on wedding invitations, but they are not necessarily suitable for everyday use.
The reason that we mainly use plain (sans serif) fonts in presentations is because they are more readable. Readability is about how distracted you are by the characteristics of the typeface. So when the ‘g’ has a lovely curly tail this can distract our brains from the message contained in the text. Anything that makes the typeface more interesting, such as thick and thin strokes, very tall letterforms or short stubby ones can distract us from the message and in some situations, its important that we get the message very quickly. You never see serif fonts used in road signs, for example.
Strictly speaking, readability is about how easy it is to read long sections of text (otherwise known as body text). So it would be OK to use a more decorative font for a headline or as a special effect, but keep in mind that every element of your slide should be there for a reason and this includes fancy fonts.
So what typefaces would I recommend? My personal favourite is Calibri, but any nice plain font such as Helvetica or Futura will do.