Mark Meer is one of this generation's worst voice actors, delivering every single line in a dull, lifeless monotone and raising his voice with all the authenticity of a kindergarten stage production of Robin Hood. He's saved from being the worst voice in the Mass Effect franchise only by the presence of an uncharacteristically hammy and subpar turn by Gwendoline Yeo in both games as Shiala and Sha'ira. What the hell happened to you, Gwen? You were so good in Final Fantasy X-2.
Jennifer Hale, on the other hand, is pretty much a shoe-in for the video game voice acting hall of fame. Every single thing she shoots for is a roaring success, and nowhere is this more apparent than in the Mass Effect series, where regardless of Shepard's alignment, she is unquestionably believable.