Isn't the feel of the Nexus 5 versus the OnePlus One a purely subjective matter? Once you hold either one in your hand, you either like it or you don't, right? I suppose you could always change the back of the OnePlus One to wood, carbon fiber, or denim to make it feel better. The Nexus 5 doesn't have that option.
As for support, the OnePlus One is an official CyanogenMod phone, so it has that.
I don't think OnePlus really needs a subsidy as long as they sell every phone they make. That's the impression I get from their crazy invite system. However, if they make too many phones that don't sell, then they'll be in trouble.