Pretty much those that have already been said, the Flippin Zip and Thump grubs are musts for minnow imitators; I would also choose a craw imitator such as the double tail K-Chub or maybe the mud bug.
However, when I'm "power" fishing for them in the colder water, I regularly use the 6.5" ribbed ribbon tail worm and the 4.75" smokin' shad for walleyes. Whether it is their appetite at that time of the year, the fact that these bigger baits are easier to find in the spring current, or a combination of both, the bigger plastic will out-fish the smaller stuff on most occasions. (One of my buddies that I turned on to the ribbon tail doesn't want to fish anything else since he's seen how well it works... even when I'm mopping up on a thump grub, he stubbornly stays on the ribbon tail hoping to get a big female.)
