Keramicks don't work for me. They are smooth but they don't cut at all and the four glue globs over hanging the blade edge on the blade are off-putting. I will be trying Superiors in my blade test in a few weeks.
I think I would rate the Keramiks a little higher than the Platinums too, but the difference isn't that big. Like most P&G/Gillette blades they start a little rough for me but I certainly can live with their 2nd and 3rd shave.
The SPs are my blade of choice right now. They're a bit smoother and sharper than my back up RedPack Personnas. I can get equally smooth with Reds and Astras, but the Astras don't irritate me at all.
I don't have a ton of experience with different blades, though. I've not tried a Feather yet, but the Astra SP works better for me than Derby, Dorco (300 and 301), Crystal IP, Merkur, Wilkinson Swords, and Red Pack Personnas.