Giles is thought of as a one and done, with Nichols having to sit a year out that doesn't really effect him, but yes Duke does have some quality front court depth besides Giles.
As for uncertainty, there's also uncertainty with the Virginia/Wisconsin situation, unless Nichols' family is gonna get some sort of binding agreement in writing for Bennett, other coaches will definitely be making Nichols' aware of the fact Bennett is considered an option for the Wisconsin job.
Also, if you simply want to argue who gives him the best chance of getting into the league which clearly is his families top priority, Barnes & Tennessee can make a better case than Bennett & UVA, and I don't think that's really even debatable.
Let me be clear, I'm not saying he's coming to Tennessee, I'm just passing along what is being said and making a case for the Vols.