George Washington never purchased a slave (he inherited them). He never voted for anything pro-slavery in the Virginia House. He had a field where the slaves could farm and keep all the profits for themselves. On his death, he set his slaves free.
I’d say all in all, Washington’s record on slavery, given where and when he came into the world, was pretty damn good.
Many of the slaves at Mount Vernon were not his slaves but slaves inherited by Martha, and he had no legal authority to free her slaves. He provided for his own slaves to become free at her death but also wanted to avoid breaking up families—and some of his slaves were married to some of her slaves. It was a complicated situation since he also needed to figure out a way that the former slaves could make a living—in an economy very inhospitable to free black workers.