One that got good marks was a dwarf, curly leafed type. Very drought tolerant. These are some of the most used bedding plants available. They are virtually trouble free, but I have had trouble with aphids causing distortion of the foliage and browning of the flowers. They are generally considered a shade plant, but do quite well in full sun in Bay Area, given ample moisture.
All varieties are a delight and grow best in light shade with ample moisture.
Two varieties that I'm particularly fond of are 'Cobalt' and 'String of Pearls'. A newer variety which we grew in our plot, has extra large flowers and is called 'Blue Butterfly'. It deteriorated earlier than all the other varieties under drought stress. It is very drought tolerant and blooms almost year round, being in its peak during the fall. This is the beautiful dwarf purple flowered and purple velvet stemmed plant that is really a perennial, but is often treated as an annual.