Is the USA today poll not considered major? Not challenging you, but just asking.
The odds against Bernie winning the Iowa primary are +157. I think this is the value side. The polls indicate Biden has a good a chance as Sanders, but I don't have any knowledge of how the ground game works, so could be a bad bet. Seems to be quite a bit of Bernie hype in that line though. Also, like the fact that Bernie is tied up in the senate and has to rely on surrogates to fire people up.
Looking at the 538 simulations, Biden and Bernie are essentially neck and neck in Iowa, where each has a 36 and 35% chance of winning the most delegates respectively.