Kai. As always. Current blade is on about its 10th day. Kais are very economical because they last a long time. I bought a bunch of very cheap Silver Stars once and found that for me they really are only good for one shave each! So they're actually more expensive than Kai blades.
I also find that Kai blades make my pre-WWII Gillette Tech just slightly more aggressive (because they are just slightly wider than standard), which helps it.