As long as you got a legit product, both are excellent. Now depending on your dosage per day one or the other might be better for you. If you only plan on running 25mg/day than you'd be better taking the 5mg tabs so you can space them out throughout the day. If you're planning on running 50mg's per day than the 25mg tabs would be great. One in the morning and one in the evening. This is due to it's short active life.