Not the biggest Lincoln fan, but Gregory Peck's Lincoln deserves a lot of credit from the The Blue and the Gray. Gregory Peck put more work into that role than most actors did back then, and wanted to do it. Rip Torn in that mini-series did the same thing with his Grant, fighting the directors to wear a private's sack coat with Lt. Gen. rank instead of the double-breasted frock coat they had for him.
Hal Holbrook's in North & South was pretty good as well.