I think they should have all non-playoff teams have an equal chance at the first five picks. All 14 teams names go in a bowl and you draw out five.
That way there's no extreme tanking. I mean I guess if you want to try your best to get the #6 pick if you're the worst team in the league and don't get one of the top five picks you could tank.
But the difference between #6 and #12 most years is non-existant. It's based on how good you are as a talent evaluator. Those picks are basically a crapshoot (6-12).
Then teams who might get the #8 playoff spot may tank. If you're a .500 team and you have the option of landing Lebron James in the draft by missing the playoffs or getting swept by a strong #1 seed, Lebron starts looking mighty attractive. There's essentially no system beyond an entirely random one (the wheel would be one, though I think it's a bad idea) that doesn't support at least some level of tanking.
A major problem with something like the wheel is that all drafts are not created equally. Get one like the one in 2011 or 2010 and the team that gets #1 that year is really in a bind. And truly random system could doom a team to mediocrity or worse for decades. And again, the Wheel is already off the table. It's really a pretty poor idea in a league that is so top-heavy with talent. Unlike the NFL or MLB, in the NBA guys outside the top 10
rarely become true team-carrying superstars. While everyone can rattle off a few, it just doesn't happen enough to make it anything more than almost a completely random chance.
Re-weighting the odds - something that's being considered right now - is probably the best solution. It minimizes (but does not eliminate) tanking at the very least while still giving bad teams the best opportunity to improve themselves through the draft.