Since you did say "best" ... a pair of Canon 600Ex-RT speedlights and you might also consider getting the ST-E3-RT transmitter. A 600EX-RT can work as a "master" or "slave" (so it can be the transmitter). Put one on-camera as the master/transmitter and decrease the flash-exposure compensation on that flash so it works as "fill" light to reduce harsh shadows when shooting outdoors. Use the off-camera flash for key light. The radio is rock-solid and does not require line-of-sight. Also, the on-camera controls can control pretty much EVERYTHING on the off-camera flash -- which means that even if you put the flash inside a soft-box, you don't need to open the soft-box to change flash settings. )
When I'm shooting indoors and need a flash (events) I typically put a 600EX-RT on camera and a Rogue Flashbender attached (btw, it needs to be the "large" size). The Flashbender helps especially when the room isn't conducive to "bouncing" the flash.
If I'm shooting outdoors then I remove the Flashbender, point on-camera flash straight, but dial down the power (if using E-TTL just set the the Flash Exposure Compensation (FEC) to about -1) to use it as fill and control primary lighting either using sunlight or by using the off-camera flash (a portable soft-box like a Westcott Rapid Box or a Lastolite EzyBox Speedlight helps.)
