for quality build, to go with top quality hardware, you might aswell go for a tier 1 PSU since its the critical system part,
if you were on more of a budget go to next tier, but if you are already going for top of the line hardware, make sure you pair it with an equal top of the line, tier1, psu, to further eliminate any troubles
and the absolute max wattage you need from a tier 1 PSU to power any single card build(980ti, titan, AMD), with OC, is 650watts, no need to go higher
if you start to think about SLI, then 850w on tier 1 psu should be your minimum