Charles Beard for one. He was considered the leading historian in the first half of the 20th century. His view is that the war was mostly about money. he was from Indiana originally and was on the faculty at Columbia so he was hardly a Southerner.
For my part, I don't place much stock in the opinions of other historians. I prefer to look at the original sources and see what they said before the events and during the events in question. I can do the interpretation myself. I don't require an Academic to tell me what my opinions should be.
In recent decades, a clutch of historians -- most prominently the late conservative Forrest McDonald -- effectively demolished the Beard Progressive interpretation by thorough original research in letters, diaries, and newspapers.
Of course, in any sort of research undertaking, one must guard against the fallacy of confirmation bias in which alternative explanations are ignored. In that vein, just why do you reject the abundant references to the defense of slavery in the Confederate articles of secession as stating the motive for secession?