Once Upon A Time's choice for Arthur I really liked, Liam Garrigan. All their casting for Arthurian characters was great, actually!
Morgana is Julianna Margulies to me and it kills me all the time that she only ever played Morgana in Mists of Avalon. Someone please hire her to play a middle aged Morgana in any kind of King Arthur production ever, somebody, please.
Lance for me changes too much but for the past few months, thanks to the constant Lancelot references in Hamilton, I see Daveed Diggs now.
Also I noticed when I uploaded the art I commissioned of my Guens, only one went through (which is what I get for posting with my iphone) here is my other Guenevere:
For face castings for my Guens, I like Lena Headey's Guinevere for my ace!Guen in the Merlin miniseries.
And for canon my canon!Guen I like the Guinevere that was played in a production of Camelot near my town, WHICH I WAS SUPPOSED TO GO TO BUT DIDN'T END UP SEEING, I'M SO BITTER, Brittney Coleman.