'Mr. Optimist' is one I'll recommend, this year by far the earliest and most heavy flowering within my collection.

I wouldn't worry about easiest, what is easy in one climate is difficult in another. If you want to learn how to grow dahlias look at some of the 30 or so short videos Kristine Albrecht has on growing dahlias. She is a famous hybridizer, bu more importantly for us backyard growers, she is one of the BEST teachers in the country! She does live on the California coast which has a good climate for growing these beautiesl. Christine Albrecht wonderful dahlia instructor in California