OTOH, if you favor States rights then Lincoln was one of the worst...if not the worst President of all time.
To put Lincoln's Civil War conduct into context, I think we need to look at Jefferson Davis's heavy handed reign in the Confederacy. I think Lincoln comes out much better in the comparison.
I have always found it odd that the neo-Confederates blast Lincoln for suspending habeas corpus but not a peep about Jefferson Davis doing the same thing, several times. I'm not really too critical about either president doing that, BTW. It was a time of war and sometimes extreme measures have to be taken.
If slavery wasn't the prime issue of the war, what was the grievance that so serious that the southern states had to succeed? There seems to be no issue or issues in combination that approach the level of concern about slavery. To say that slavery wasn't the primary cause seems a bit disingenuous.