ILikeLizards

If the project you want to do follows the tight DOE guidelines, then perhaps taking the extra money is best. But if you want to have flexibility to shape your own projects, NSF is best. It also depends on if you're going into academia vs industry. In industry your project won't matter as much, but for academia positions being hired will depend largely on the publications and research you produce as a PhD student. For academia, the couple extra thousand will matter little if you don't get hired by the University you want, and the area you want to live in. It all depends on you!

Generally I've heard the NSF is the most prestiguous, and will help you get better positions in the future. That is followed in prestige by the NDSEG award. With the potential long term income swings, I would say the stipend amount matters little. Make sure you have the right reasons when making your choice. Good luck, and Congrats!