DUK is your standard conservative regulated utility with above average dividend yield, and very modest capital growth. FPL, with its FPL Energy having a choice unregulated business (windpower primarily) has much better opportunities for capital apprecation in the future. Dividend yield of FPL is obviously less than DUK, but the dividend will increase at a faster pace in coming years than the more conservative DUK. I own both, and have peace of mind with both, even with market sell offs. I would much rather own DUK for income than a 5 or 10 year treasury with no prospects for increased income.
DUK vs FPL is a very tough choice. I suggest you go to your public library and spend time with ValueLine, to get the background information you need. You don't indicate whether you are interested in income or growth, but on both points DUK is the better choice. It has a 4.4% dividend vs a 2.7%, and the recent FPL run-up has put the price at a level where little growth is forcast for the next several years.
What I like about FPL is its longterm investment in wind power. I believe that oil prices can only increase and that alternatives will pay off.
DUK just spun off Spectra, which makes it very difficult to assess its finances, either current or for the next few years.
Try ValueLine, I have used it for years to make choices like this.