The greatest valuation will usually come from the Precedent Transactions technique, because a firm will pay a premium for the predicted synergies from the merger, out of the four basic valuation techniques (Market Value, Market Comps, Precedent Transactions, and DCF). Because those creating the DCF model tend to be relatively optimistic in their assumptions and expectations, a DCF study will usually offer you the next highest valuation. The lowest valuations are usually produced by using Market Comps and Market Value.
The another point It is debatable. It relies on the discount rate used in the DCF model, the similar companies chosen, whether the market is bullish or bearish, and whether the companies are overvalued or undervalued for no reason. Transaction comps, on the other hand, would often yield the greatest valuation because a transaction value would include a premium for shareholders above the actual worth. The DCF is probably the second highest valuation because it involves a lot more assumptions (growth rate, discount rate, terminal value, tax rates, and so on), but it can also be the most accurate depending on how strong the assumptions are.