For me it comes down to a few things. Minnows seem to work year round for all species of fish, and perhaps the best for me in the spring time. Only hassle with minnows is keeping them on the hooks while casting, and keeping them frozen. Leeches seem to work wonders for walleye, and again i've had better luck with them in the spring/early summer than in late summer and fall. Since the leeches are alive and squirming under water as opposed to the lifeless frozen minnow, I believe that that contributes a lot to the success. Additionally, leeches seem to survive multiple casts and retrieves and are quite durable. They also seem to outperform other baits in disgusting algae ridden waters like blackstrap, where I expect the walleye are used to preying on natural leeches in the lake. Crawlers tend to be my bait of choice for the hot summer months (from personal experience and experimentation, and I'm not sure why that is). But there are a few tricks to using them effectively. You can "ball" them up on a single hook, and achieve results from hungry, active fish, or you can use a rig that has two hooks inline with each other. This allows the crawler to squirm, and provide some action, and ensures that you don't miss fish due to them biting off the back half of the crawler while the front half is still affixed to the hook. That being said, Which is the best? Which one do I use? All three. I will usually bring minnows and leeches in the spring, or minnows and crawlers in the summer months, and if fishing a pickeral rig, or something with multiple hooks, I will put different bait on each one. In some circumstances I've found them to perform relatively equally, but in others you may find the minnows to greatly outperform the leeches, and vice versa. Therefore I believe it is not only up to the personal preference of the angler, but also up to the preference of the fish in the particular water body in question that should determine the bait being used.