A high yield alone doesn't make a stock a good income investment, which AGNC Investment proves. Here are two better options.If you see a stock with a dividend yield exceeding 14%, you should immediately know you have to dig deeper. That is usually a sign that Wall Street views the investment as risky, which is why most investors will probably be better off avoiding AGNC Investment (AGNC 0.49%). But you'll likely find Realty Income (O 1.16%) and W.P. Carey (WPC 1.33%), both of which have yields just above 5% ...