What Wayne wrote about flash brackets and shadows is spot on. I have a Stroboframe bracket which keeps the flash above the lens, and when I asked at my local camera store about the brackets that have the flash to the side, they said what I've got is miles better than the type they had in the store for the exact same reason Wayne mentioned.
As for which flash is best, keep in mind if you want HSS (High Shutter Sync), you will want a flash capable of performing it. Not all flashes will do so--especially when it comes to the Yongnuo brand. And not all Nikon flashes offer it either although the SB700 does.
I have both an SB700 and SB910. Both are terrific; however, I found when bouncing flash off a VERY high ceiling, the SB700 was indicating it couldn't give off enough light even when at full power (there is a blinking light that gives the indication the flash didn't have enough oomph to give adequate lighting). Otherwise, the D700 is an awesome flash.
As for which flash is best, keep in mind if you want HSS (High Shutter Sync), you will want a flash capable of performing it. Not all flashes will do so--especially when it comes to the Yongnuo brand. And not all Nikon flashes offer it either although the SB700 does.
I have both an SB700 and SB910. Both are terrific; however, I found when bouncing flash off a VERY high ceiling, the SB700 was indicating it couldn't give off enough light even when at full power (there is a blinking light that gives the indication the flash didn't have enough oomph to give adequate lighting). Otherwise, the D700 is an awesome flash.