What is your all time worst blade?

Derby Extra

Wilkinson is a close second, but the worst I've had so far is BIC. I couldn't even get through the first pass.

+1 on the Voskhod for me

Derby

When I bought a QShave Futur clone razor, it came with a tuck of "QShave Titanium" blades.
The first time I used one of the blades (in on of my Gillette vintage razors, I forget which), I thought "Wow, this is the best blade ever! Sharp like a Feather, but smooth like an Astra SP".

The second shave with it was ... meh.

The third shave - just awful. Rough, not cutting well. I finished the shave with it but tossed the blade.
I thought maybe I got a dud, but at least 2 more blades from that tuck were the same. Terrific first shave, then crap. I even tried one in the razor it came with.

I usually don't consider a blade to be properly "broken in" until the 2nd or 3rd shave, and usually take them to 20 uses, minimum.
Not gonna happen with QShave Titanium.

Gillette Silver blue. My neck wants to cry of irritation whenever i used this, even my cheecks hurt. I think somehow the bevel or sometbing doesnt agree with my face. And i have tried them dozens of times on ablut 10 diff razors.

Give me: feather, polsilver, med prep and astra sp,

The very worst is the Merkur blade. 

Second place goes to Derby. Their blades always feel rough to me. 

And in Third is Feather. I know this blade has a loyal following. More power to those who love it.

So for me it’s a Feather. I started out shaving with my Grandfathers Gillette Superspeed and my technique was horrible. I got a blade sample pack and tried out GSB, Astras, and Polsilvers and got horrible shaves. And so I settled on feathers because they were efficient but they are my face up. I don’t know why I stuck with them for so long.

For me the worst blade I used was Tiger blade

For me the worst blade I used was Tiger blade

Yep, that one and Graham Field tied for my worst