My decisions were made as if the movie/TV series was to be made right now. Some of this is dream casting but most of is just people who I happen to think would be good in certain roles. I know that some of the non human characters would be tricky to cast. For Krogan you either need guys in animatronic suits augmented by CGI or just go full CGI. For Salarians and Geth it would probably be easier to go full CGI. So you would still need a lot of voice actors.
This is all of course my personal opinion and just for fun. Feel free to comment and/or add your own lists.
**FemShep:** Kate Beckinsale, Amy Adams, Katrina Law, Katee Sackhoff, Rhona Mitra
**MaleShep:** Ryan Gosling, Ben McKenzie, Sam Worthington, Kevin McKidd (if they wanted to go older)
**Garrus**: Bradley Cooper, Ryan Reynolds
**Joker**: Chris Evans (he'd make a damn good MaleShep but after years as Capt. A it would be nice to see him play more of a goofball character again)
**Liara:** Cynthia Addai-Robinson, Dakota Johnson (there are probably others who can do better but she's the best I can come up with)
**Tali:** Roxana Condurache, Paula Schramm
**Wrex and Grunt:** John Goodman or Clancy Brown might each make for a decent voice for Wrex but honestly I can't think of anyone who could do either of them better than the guys from the actual games. Steven Barr and Steve Blum
**Ashley**: Willa Holland, Kristen Stewart (after Camp X-Ray she deserves a shot)
**Kaidan:** Joseph Gordon Levitt, Brendan Cowell
**Miranda:** Zoe Saldana, Viva Bianca, Charlize Theron, Scarlett Johansson (way better with this than Major Kusanagi)
**Jacob:** Michael Jai White, Anthony Mackie
**Mordin:** Once again I can't think of any voice actors better than the ones who voiced him in the games. Michael Beattie and William Salyers
**Thane:** Wentworth Miller (again, probably others but the best I can come up with)
**Samara:** Michelle Fairley, Gillian Anderson
**Jack:** Rooney Mara, Jessica Chastain
**EDI and Legion:** Not really sure. You know, what if they got Jennifer Hale and Mark Meer to do each of the voices? That would be amusing.
**Zaheed:** Sean Pewtree, Vinnie Jones (either one would so freaking awesome)
**Samantha:** Lesley-Ann Brandt, Shelley Conn
**Vega:** Honesly, I already know that Freddie Prinze, Jr. can speak the role and I can't see any other Latino American actors physically doing the role live action. I do not say this as a Prince Jr. fan. James Vega (a video game character) was probably the best performance that he's ever done and he's got a pretty decent sized filmography.
**Cortez:** Amaury Nolasco
**Anderson:** Idris Elba, Tony Todd
**Illusive Man:** Gary Oldman, Josh Brolin, Dean Stockwell
**Hackett:** J.G. Hertzler, Charles Dance (if they decided to go British), Malcolm McDowell (again, if they decided to go British)
**Saren:** Ian McShane
To be completely completely honest I would mind at all if Yvonne Strahovski, Keith David, Martin Sheen and Seth Green physically reprised their characters in live action.
In addition I'd want Joss Whedon to be Director and/or showrunner, Stan Winston Studio to do all the all the make-up and animatronic effects, Patrick Tatopoulos Designs, Inc to do all of the Geth and EDI stuff, and ILM to do all the other CGI.