Although I delight when I hear Keith David in Mass Effect or any game, I can reach farther back in time memory: Keith David will always be this wonderful man to me:
As far as "voice actors" go. I personally think Keith David is objectively better. That's not to say what lance Reddick did isn't iconic and can never be replaced the same. But it's a great choice to follow such a great act.
What I meant by that is that Lance Reddick has a very unique voice, and it will be obvious when he has been replaced. Yes, I think as an actor Keith David is better. Lance Reddick really fit the character, though.