I actually do think the CSA is pretty clearly the lesser evil here. A Southern victory may have been worse for a short time, but today we would be better off. Slavery would have ended a long time ago, and we'd either have one constitutional republic, or two. We would not have the modern day empire. As such, I absolutely wish the South had won, with all due apologies to those who would have been negatively affected by this. I can say, however, that Jim Crow would almost certainly never had happened if slavery had ended by non forcible means.
I'm not saying the Confederacy was all dandy. But they were the attacked. The Union was the aggressors against the Confederates, who wanted independence. The Ft. Sumter attack was stupid, but ethically right, Lincoln had no right to keep the fort, which, for the record, the South did offer to pay for.
And the Lincolnian Leviathan victory created the greater evil.