In the USA it is common to think of scones as baking powder biscuits with added richness from egg and sugar. Raisins and other addins are common. In the UK scones can be the same as American biscuits (their biscuits = cookies).
Apart from the addins, the 'simplicity' of biscuits/scones varies mainly with your choice of fat. Ones that use heavy cream as both fat and liquid are perhaps easiest to mix. Another easy idea is to grate a frozen stick of butter into the flour, and lightly mix.
The other variable is how they are formed. A wetter dough can be dropped by the spoonful on the baking sheet. A stiffer dough can be patted out (or rolled) and cut into disks. Or for a shape many associate with scones, pat the dough into an 8" circle, and cut into wedges. I've even spread a dough in a cake pan, and cut it into wedges after baking.
There's a current thread on 'best biscuits' that is relevant to scones; and another about achieving an ideal crumb in scones.
I've had very good luck with the buttermilk scones recipe from a blog called "the dinner files." Last time I made the full batch to the point of cutting the butter into the dry ingredients. I split that in half. I added the buttermilk to half and baked, then froze the other half to bake another time. My idea is to have a sort of homemade scone mix on hand, but as I haven't tried the second batch yet, I can't be sure it'll work.
Yeah, I don't agree that scones require eggs, or that without eggs they are biscuits. And the very simplest to make are the ones with just heavy cream, as smfan says - no eggs or cutting in of butter. And they're not biscuits in my book but classic scones for tea, very tender and light.
Here's the recipe. Add a half cup of currants, raisins, or other dried fruit if you desire. Stir it into the flour mixture before you add the cream.
2 cups AP flour
1/4 cup sugar
1 T. baking powder
1/2 t. salt
1 1/4 cups heavy cream (plus more if needed)
Preheat oven to 425F. Stir flour, sugar, baking powder, and salt in a mixing bowl. Stir in any additions such as raisins. Pour in 1 1/4 cups cream and stir to incorporate all the flour mixture. If you can't incorporate all the flour in 10-15 strokes, drizzle in a bit more cream (I often need about a T extra). Turn the dough out on a floured surface and knead gently once or twice to bring together. Pat into a half-inch-thick round and cut into wedges with a floured knife, or cut with a floured biscuit cutter. (This will make 8 or so 3-inch round scones or around 15 2-inch round.) Place on a baking sheet lined with parchment or silpat, and bake until just golden and firm on top, about 15 minutes depending on size.