A couple months ago I proposed a system to prevent tanking without changing lotto odds, called Pick-Swap. It's based on the idea that if you trade your draft pick away, you're no longer incentivized to tank.
Here's how it works. Before the season begins, teams are heavily incentivized to swap draft picks with each other. Teams who don't swap could be prevented from getting a top-3 pick. Bad teams will swap with other bad teams, of course, so there is still an incentive for the front office to tank in the preseason, so that you can swap picks with another bad team. But once the swap is completed, all tanking incentive is eliminated. No longer will you have to root for the C's to lose; you'll be rooting against the Magic instead, or the Lakers. Moreover, games between teams that swap picks will take on special importance. By beating that team, you can actually improve your lotto standing!