Key points to consider:
1. Care: If you are meticulous about taking care of things, a pastel will be a good choice. Pastels really need to be kept away from humidity. They also need to be kept from bright light or they made fade. In addition they are more fragile, as they are framed in glass and are created on paper.
Having said that, Mary Cassatt's (1844-1926) pastels are legendary and have survived a hundred years. When I visited the Louvre I saw amazing pastels by Maurice Quentin de La Tour (1704-1788) and the Jean Chardin.(1699-1779) There is something in the fragile nature of pastels that is extremely compelling as well! They are endearing and treasured—— but must be cared for as well.
2. Style of portrait: pastels are generally a vignette and slightly more sketchy in appearance. You'll see in oil portrait below, how I was able to recreate the "vignette" feel by painting on a toned canvas. I did this to match the look of pastels of family members from prior generations.
3. Cost: Generally framing will be higher for a pastel, so the price will be about the same for a framed pastel vs a framed oil.
Here are a few samples of my work in these mediums below. You can click the links below the images to go to my website for more samples of these types of works.
Oil Portrait: Maisie

www.soniahale.com
Pastel Portrait: Bonnie

www.soniahale.com
Sonia Hale is an award-winning, nationally-collected artist in Boston. She paints commissioned portraits for families and institutions nationwide. Her original landscape and still life oil paintings can be purchased at http://www.soniahale.com. For more information, go to http://www.soniahale.com. You can reach her by email at soniahale1@gmail.com.