I prefer dividends as they are an instant catalyst in realizing value from a stock. Buybacks do not do that. Buybacks in theory raise intrinsic value, but I don't care about IV, I want to see the price of the stock go up. My nightmare would be an IBM situation - management burns away ridiculous quantities of cash on buybacks and shareholders are left with a low stock price.
What's more is that management is terrible in using buybacks.