I would have liked to have seen George Peppard’s take on Blake, instead of the sort-of-grandfatherly man that he became with John Forsythe playing him.
Peppard was a good actor, but he had this asshole-y quality about him which made him quite unlikeable. Forsythe could do "cold" but also cuddly, and I'm not sure Peppard could bring that range to the role.
After A-TEAM became a hit, Peppard was cleverly gracious enough to say he didn't think he could have brought "the layers" to Blake Carrington that Forsythe did.
Less known is that producers approached Cary Grant to play Blake, but he'd retired from the screen 15 years earlier and was working on his signature Faberge line of men's products. But when they wanted Forsythe, ABC felt he was "too old" (despite being 14 years younger than Grant!). Same with Joan -- the network had no problem with Elizabeth Taylor or Sophia Loren as Alexis, but Joan was suddenly "too old" (despite being the same age as Taylor and Loren).
But Cary, Elizabeth and Sophia were icons, so their ages didn't matter. John and Joan were just known working actors, and not icons -- at least, not yet.