What is best to take to lower cholesterol? niacin, niacinamide, no-flush product? and how much?

Depends: Which lipid class you will be treating, so it might not be niacin.

Niacin is best: No-flush Niacin can either refer to a slow release preparation or inositol. Slow release preparations are better tolerated than immediate release products, but the lipid lowering effects are somewhat less potent than immediate or extended release niacin. For comparable efficacy a higher dose of slow release is usually needed. Inositol and niacinamide not improve lipids and should be avoided.