Here's my picks and my reasoning:
The Riddler : Benedict Cumberbatch
Jim Carrey played the Riddler more like the Joker in Batman Forever - too over the top. I think he has to come across as playful but in a more methodic, focused and calculated way than the frenzied joker - highly intelligent and articulate but a little eccentric perhaps. Cumberbatch can do that in his sleep.
Ras Al Ghul : Pedro Pascal
Foreign exotic looks, measured and extremely self confident. All qualities I felt Pedro Pascal showed in GOT.
Two Face : Nikolaj Coster-waldau
Handsome (on one side at least!), suave, but capable of flipping between good and bad at any point. Another GOT actor who can do that. He's actually not a million miles in looks away from Aaron Eckhart, which I think isn't a bad thing as he played a great Two Face.
Penguin : Eddie Marsan
Terrific actor. I think the Penguin role is difficult to cast as there are some strong physical/aesthetic considerations, but Marsan could do it justice.
Scarecrow : Stephen Merchant
Scarecrow is usually masked so facial resemblance isn't a consideration here; more so the fact that I want an actor who's fairly lanky/thin, and who can do a convincing job of being creepy and a little unhinged. Merchant just did a great job of Caliban in Logan, and I think he could manage this too.
Hugo Strange : Bryan Cranston
I mean .......... it's just gotta be? With a little bulking up.