I can't really name one because they usually get frogged. I can say that I've had more problems with crochet patterns than knit. But because that's a lame answer, I definitely think my least favorite was the first time I tried to knit socks. They've since been frogged, but I have the pictoral proof.
I started last April, a nice variegated baby yarn to get me into the hang of knitting them before I moved on to my nice sock yarn. Everything was going ok, all 8 inches of ribbing, except for a few ladders. I put it on hold for a while (actually, until October) when I came back and decided I didn't need to sit in a quiet room when starting the heel, how hard can it be? (I usually watch TV or movies when I knit.)
I ended up with this:
See the problem? Most socks are supposed to look like this:
...where the heel is on the same side as the cuff. In my picture my heel is on the left side and the cuff is on the right. I turned the heel perfectly fine, it was just on the wrong side of the sock!
I debated continuing and making a hybrid monster sock thing, but eventually decided to frog
But hopefully soon I'll knit that cake of yarn into a legit pair of socks.