It's like 6 of one or a half dozen of the other. I've used them both. 20 years ago only the generic ECA stack was available. I like it much better. For one thing it's less expensive. About 20 cents for a 200mg caff, 25mg Eph HCL, and an aspirin tablet. Anytime these companies start mixing everything together they also mark the price up. It's called marketing and it's purpose is to get your money into their pocket. This is the cheapest site I've found. There are probably more.