I like the Whitings 100's. I especialy use them for Adams Parachutes which I tie in quantity, but only in a limited range of sizes. I can buy a size 14 pack and not have to waste a bunch of feathers that ar too large or small for the task. I thinks it's a great product.
I also like to dye them for odd one of a kind uses. I have a pack of size 10 grizzly that I might pull enough feathers for 2-3 flies and over dye them with yellow or olive. Now I can tie up some big green drakes, a fly I only use once in 2-3 years.
Metz also packages a pre-sized product. They divide a regular cape into three sections and package it as small/med/large.
You can buy the medium size package in brown/grizzly/dun and have enough material for almost every western mayfly pattern. Good for travel too.