Worst for me is easy: the OE GY Assurances (225/60R18, not the ComforTread) on my 2007 Magnum R/T. They did nothing well except wear like iron-grip was fair, noise levels were unacceptable (they were as loud as my Winterforce snows), and performance in snow was zero. The police Eagle RSAs (235/55R17) on my Vic (came with it when bought) were nothing special...good dry grip, OK in rain, poor treadlife (as expected, with a 260 wear rating), and loud.
Best...car, the 235/70VR15 CHP Eagles on my Caddy. Good grip, surprisingly quiet, good in rain. Sadly, they're gone (as expected, they were not a long-wearing tire), and long discontinued.
Best, winter: the Mastercraft Glacier Grip IIs (215/75R15) on my Dakota...they got me through the worst winter in 60+ years, in a short-wheelbase, high-torque 2WD pickup! Not nearly as loud as I expected, decent wear, good in the rain, spectacular in snow.
Best, truck: I am quite impressed with Treadwright's Kedge Grip studless ice tires, especially on my 92 F-350. (235/85R16E) They saw hard use, running 80psi and loaded to their full weight capacity in back (both axles at maximum capacity, truck ~1200lbs over GVWR) when plowing, lots of tight maneuvering while heavily loaded...no funky wear, no chunking, superb traction. They were a bit loud, not surprising for an all-terrain tire.
Honorable mention: while still new (~1000 miles), I am pretty impressed with the Riken Raptor ZRs I just put on the Vic. They track well, they are very quiet, and they seem very good in the rain. (I'm sure snow performance would be awful, but I expected that.)