Great thread...no pun intended...lol
For me it's the Simplicity Rotary Cutter and Bias Tape Machine. I am just totally unimpressed with both of them! I can't get the rotary cutter cranked down tight enough so the fabric doesn't slip and slide going thru. Results are strips that are most definitely NOT straight, unuseable and wasting the fabric! I like the bias tape maker slightly better and hopefully with some practice I can get it to work correctly. BIG WASTE OF MONEY on my part!!