This article Tipping point’ in annuity options for Middle Britain by Fiona Murphy speaks about the virtues of investment based annuities.These annuities have a floating,rather than a fixed income each year, as the investment changes value from time to time.
And that is the whole problem. If your memory is bad and you have forgotten what happened in 2008 in the stock market, then an investment annuity might be the ticket.
But if you remember plunging stock markets, problems in Greece, Cyprus etc, you might want to consider an annuity where the income is fixed for life.The real question is whether you can afford to get less income than a fixed annuity provides.