I made two simple loaves (flour, salt, yeast, both W/ 8% suger), but I experiemented with vegetable oil versus butter.  One loaf with 8% oil, and the other with 8% unsalted Butter.  2 hour rise, then shape, then 1 hour proof.  Oven at 450, baked till centers were 200 degrees. 

1st one had VERY distinctive vegetable oil taste and smell compared to the one with butter.  Side by side, you would taste both, and want to through the one with Vegetable oil away to the birds.