i've only tried gillette 7 o'clock in the green box from russia. i used to strictly use Astra SP. i feel like the gillette blades are sharper than the Astra. Sharper might not mean better though, but for my beard they were better.
I just shaved with the 7 o'clock black blade 20 minutes ago... It's a very fine blade, and the first shave does seem a bit smoother than the Astra SP. Just a bit though... For me, the Astra is the Olympic champion, considering price and performance. They rock. The Gillette branded blades that are made in the same factory have fancy wrapper art, the Gillette name on the wrapper, and cost a bunch more than eastern market labels like Astra. I love to shave with a variety of blades, but sometimes I lose my reference base, and forget just how good the Astra blade really is. All it takes for a reality check is to switch out a premium label blade while it is still in prime condition, and replace it with a new Astra blade. That puts everything in perspective again..