As long as the Joker is written and acted well, it will always be him for me. He's the greatest villain of All-Time IMO. Don't care for his appearance but Leto looks like he's going to nail the acting/characterization. I'm also really looking forward to Harley Quinn because I think Margot Robbie is basically the perfect casting choice and she also looks like she's going to nail the role. Looking forward to the two them interacting together as well.
I'm very intrigued by Enchantress, because her character is very unknown and mysterious to me, as is the actress. Killer Croc is next on the list, he looks fantastic on film compared to the set pics, I'm much more excited about him now after seeing the trailer. He should end up being a really cool physical threat character with some cool action scenes. Captain Boomerang looks like he could be interesting, I think this is a good role for the usually pretty dull Jai Courtney. I think he'll have some cool scenes too.
I'm normally a really big Deadshot fan but I'm lukewarm about him so far. I'm sure Will Smith is a good fit for the role the way they are interpreting it but so far it seems like he's going to be the moral center of the Squad, a sympathetic villain and I'm not too found of that route. It's what I expected when I saw Will announced as the character because it plays into Will's strength's as an actor but it's not as interesting to me. I could be wrong, we don't know alot but judging from all the set pics and the trailer it looks like he's going to be more of an anti-hero than a straight up villain/assassin. I don't dislike this possible take but I would have just preferred a more detached, mission focused, heartless loner Deadshot that sees everyone as potential targets.
I don't like Jesse Eisenberg as Lex at all. I'll just leave it at that, been through that argument enough. Slipknot and Diabalo just aren't interesting to me at all, they are just cannon fodder played by two very mediocre actors. Waller is Waller, she just barks alot, she doesn't really DO anything, she is needed in her role and I expect Davis to be good but she's more of a support antagonist than an actual villain.
I like the Rock, but I just have no interest in the Shazam movie at all. I don't like the Shazam character, it's the one DC movie I'll probably skip.
Hoping for and looking forward to Doomsday and Darkseid in future movies.