My personal preference: In all my builds I use EVGA G2 PSUs. Great warranty, gold rated efficiency, great quality, full modular and all sleeved cables. While you'd be "ok" with a 550 I find its always better to shoot high for future upgrades & keeping load under control (can help with fan noise also), so I'd probably go minimum 750W since the cost difference is typically negligible.
The new G3 PSUs are getting good reviews until you get to the 1000W where fan noise becomes an issue. The G3 is nice simply because of its more compact size.
You'll find different people have different favorite brands. Your budget also makes a difference.