Hiya,
I found my favorite two blades years ago, and I'll use those almost all the time. They're especially handy when trying a new razor, and it's usually pretty easy to tell if that's gonna be a good fit or not.
Sometimes people will send me blades to try, and I have no problem giving em a shot in my control razor. Only takes a couple strokes to know if they fit or not, and it's easy to toss it away if it doesn't work out. Some good blades I've tried that way have been Lion and Shark ones.
I'm lucky because I will sometimes find vintage Gillette and Schick blades in the wild, and if they're stainless steel I'll usually grab em and see what happens. Blades like the Gillette 'Spoiler' and Schick Plus Platinum are good ones, and those blades have plenty of fans. Even though some are 30-40 years old, they still perform pretty darn well. Not as good as my favored Iridium, but much better than average. I should also mention the price for these is always next to nothing..maybe a few cents per blade.
Heh, there's been a few vintages ones though..................just amazing blades. Certainly as good (or maybe even better )than the Iridium, which surprised the hell outta me when I first tried one. Extremely sharp yet forgiving, and they gave me an extra 2-3 shaves per blade.
Yeah, trying a new blade is always worth the 30 seconds needed to see what the deal is.
Martin