Just read Baptist, "The Half Has Never been told". One secondary argument he presents is the misinformation campaign regarding southern secession and the causes of the civil war. He calls the states rights argument too "abstract" and cites the numerous instances slavery was mentioned as a point of contention during the crisis. Also, the fact that slavery itself was the "states rights" issue being fought over. I just don't see how you can argue that it was a "states rights" issue and not a "slavery" issue besides Baptist's claim that it's a whitewash attempt to minimize the impact of slavery on the American economy, industrial revolution, American way of life, and Civil War.
Talk about the unrelated English Civil War? Stick your head in the ground and yell about state rights?
In any intellectual honest conclusion from the evidence we have, from every view point, the Civil War was about slavery.
The state rights arguments view point, as you alluded to, the only states right the Southern states cared about was slavery. In the Declaration of the Immediate Causes Which Induce and Justify the Secession of South Carolina from the Federal Union, the first of multiple "Declaration of Independence" for each of the Southern States, makes it very clear they are unhappy with the North because of their "infringements" upon the right to hold slaves, in particular Northern states ignoring the Fugutive Slave Acts.
"No person held to service or labor in one State, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up, on claim of the party to whom such service or labor may be due." This stipulation was so material to the compact, that without it that compact would not have been made. The greater number of the contracting parties held slaves, and they had previously evinced their estimate of the value of such a stipulation by making it a condition in the Ordinance for the government of the territory ceded by Virginia, which now composes the States north of the Ohio River. (Emphasis added)
Several of the other such declarations either direct mention or clearly allude to slavery.
EDIT: I forgot about Mississippi's absolutely absurdist declaration on the importance of slavery.
Our position is thoroughly identified with the institution of slavery - the greatest material interest of the world. Its labor supplies the product, which constitutes by far the largest and most important portions of commerce of the earth. These products are peculiar to the climate verging on the tropical regions, and by an imperious law of nature, none but the black race can bear exposure to the tropical sun. These products have become necessities of the world, and a blow at slavery is a blow at commerce and civilization. That blow has been long aimed at the institution, and was at the point of reaching its consummation. There was no choice left us but submission to the mandates of abolition, or a dissolution of the Union, whose principles had been subverted to work out our ruin. (Emphasis added)
The next usual argument is the "economic argument," that the North and South went to war because of their vastly divergent economies. In a way this is true, the North and South had different economies... except the biggest difference between the North and South was that the South had slaves. Cotton was king, but it is also extremely labor intensive. The best way to make cotton production profitable is to have workers who never had to be paid.
The final argument I tend to hear on rare occassions I have heard the "it wasn't about slavery because only a small percent of southerners actually owned slaves. This argument just falls apart in multiple ways. 1) Most of Europe during the middle ages weren't nobles but plenty of people died in squabbles over titles or dynastic disputes 2) Most of the actual politicians who signed the declarations of independence were either slave owners directly or tied in with industries that benefited from the slavery 3) poorer whites feared losing their jobs to newly freed blacks 4) quite a few churches in the South preached that Black men being cosigned to slavery was the literal natural order of the world that must be obeyed.