Cpu/gpu will always be king and mobo will not affect their performance; aside from pcie lanes if sli/cf. Imo, psu would be next, and then mobo, ram, hdd, case. But in the great scheme of pc building, all parts matter. If one fails, the pc most likely won't be running. Generally more expensive boards are better but every good company has cheap good mobos. You won't have to worry about reliability or longevity as long as it's a good model. Every company isn't perfect and every company has bad models, even at the high end. Even on a $2k build, I had a $130 mobo, because it was good quality and had the features I need. Spend as much as you can on cpu/gpu: what really matters.