Hi Marina and welcome to the Community. Your itinerary looks very good - you will be busy!
I have spoken to a contact, who is based in Killarney, regarding your main question and here is his reply -
"This is really a very hard decision to make as both of the peninsulas are very beautiful, however I feel that the Dingle Peninsula should not be missed.
It is much smaller in size and less travelled than the Ring of Kerry. It has some of the most magnificent mountain panoramas, golden beaches, coastal views and lively towns and villages in Ireland.
Dingle Town is the main area of population on the peninsula and all roads lead from here to all the major visitor attractions. Much of the area is Irish Speaking and visitors have the opportunity to hear the language in it’s native form.
There are also many monuments that date from pre and early Christian Times like standing stones,churches, beehive huts, stone circles and ancient crosses. So there is a strong sense of an eventful past along with a most spectacular landscape with light and colour. An excellent website for the Dingle Peninsula is www.dingle-peninsula.ie
I hope that this information will be useful when making your decision.