Here are a few to consider in addition to the ones youve already tried:
Derby Extra - made in Istanbul. These are my favorite all around blade, you can buy them by the hundred for about $20 shipped on eBay. Not as insanely sharp as the Feathers and not nearly as prone to nicking myself either. They give a nice shave in anything Ive used them in (Merkur HD, Progress, Gillette 1-9, etc)
Israeli Platinums - These are probably a cut above the Derbys in sharpness yet still a nice shaving blade, at about the same price on eBay. Most of the guys at shavemyface.com seem to prefer these.
If you live in the U.S. and would like to try them, send me a PM and I'll mail off a couple.