To echo the sentiments of a few others here, I would go with one of Seasonic's higher end models (X Series / Platinum). You really can't beat these models in terms of overall build quality, performance and they are extremely quiet (not everybody cares about noise but if you do, Seasonic certainly doesn't disappoint). Also, the Corsair AX760 and AX860 (regular version not the digital model) are made by Seasonic and are essentially re-badged Seasonic Platinum 760 / 860s.
Regardless of what brand you go with though, the PSU is the one component you don't want to skimp out on. If you're on a really tight budget, you might want to consider downgrading something to make room for a higher end PSU.
Also consider energy costs. Depending on what you pay, a high efficiency PSU can pay for itself pretty quickly.
One more thing, since you plan on overclocking, I wouldn't go below 1000W (you want to leave your PSU a little headroom). Depending on how far you push your components, an overclocked 780 will probably pull around 300W and I'm guessing around 150W for the processor. That's 750W right there. Depending on how many hard drives, fans and whatever else you have planned, you might be cutting it close even with 1000W.
Edited by ShoehornHands - 4/7/14 at 1:33pm