IMHO, neither term is entirely accurate, but I use WBTS because I think it is slightly closer to accurately reflecting the nature of the war.
Which term you prefer is generally determined by which side you feel was in the right. :)
Of course, I could have referred to it as the Great Rebellion. :)
If you lived in the South, it was referred to as the War of Northern Agression.
The War for Southern Independence.