Oh, it’s pretty clear that Grant knew Lee was the better general - he didn’t let that scare him from doing what he needed to do.
Grant’s own description of his first battle as Colonel of a regiment should be required reading for ANY military officer. His simple epiphany from that scrap guided him for the rest of the war.
If anyone hasn’t read Grant’s autobiography, they should. Wonderful piece of work.
Lincoln thought so too. Lee was his first choice to lead the Union Army.