I am a big proponent of owning quality photo equipment, and here's why. You won't need to think. Or rather you won't need to think about a technical thing at the moment you need the artistic side of the brain to be working. When on set, in the field or in the studio, you need to be concentrating on the execution of your concept not on your gear. You should know your equipment's capabilities & functions to such a degree that it should be transparent, and quality gear is designed with that thought in mind.
Here's what I mean: take for example the shutter speed dial are on your camera. You never need to think about where that control is or how to use it. It feels good too, just the right amount of tension to the detents, the knurled ring giving you the correct amount of resistance to turn it but not so much that it hurts your finger. It took the camera makers along time to engineer that dial just right. There is a direct relationship between how much time the manufacturer spent engineering the gear, and how easy it is to assimilate its function and use. Not surprisingly, all that research & development also makes the gear more expensive.
But the point is that every piece of equipment you use should be just as easy to use. Every lever, knob, button, switch system-wide should be second nature to you. Only by freeing yourself from having to think about your gear's function can you truly concentrate on the task at hand.
So, what is good gear then? Good gear is simply when good design and good function meets good ergonomics; maybe not built by photographers, but certainly built for photographers.