Neal, my experience is limited as more than 3/4 of what I have will be blooming for the first time this year. However, of those with which I do have experience, there are four that have proven to be outstanding plants. Each of these has gorgeous color, and has shown itself to shrug off heat, cold, long-term drought, and flooding rains in clay soil.
By Jeeves -- STUNNING flower, happy increaser, had a four bud socket last year! (Keppel order)
Merchant Marine - unstoppable increaser!! and look at those ruffles. (Thank you, Brad.)
Orange Harvest - lovely fragrance, consistent fall bloomer (blooms do tatter a bit in rain)
Rio Rojo -- have it in two locations and the color in each differs just enough to almost seem like I have two different flowers; increases quickly (Thank you, Rita.)