It's a fair question and one I ought to be able to answer well having flown with tons of pilots of all ages and experience level. So, I'll give it a shot.
When I think of the pilots that I have held the most esteem for over the years the one thing that distinguishes them is perfectionism. They aren't satisfied to be average. They don't fly for the glory, but the challenge.
They dissect every flight looking for ways to improve. They're serious about their business and judicious with their levity. Flying isn't "fun", but that doesn't mean it isn't pleasurable--it means it isn't a light-hearted frivolous endeavor. It's serious business and the stakes are high.
The best pilots are conservative, yet still manage a 99% dispatch rate, excluding mechanicals. They are confident without being foolhardy. They don't need to be schooled on ADM, CRM/SRM, CFIT, PAVE or any other FAA acronym because they already do those things intuitively.
They keep their eyes out of the cockpit and they slow down around airports.
They operate within the bounds considered "good practices", even if they personally don't feel it's necessary, out of consideration for their passengers.
They don't care what they're flying--they approach each flight the same. They could fly anything because their fundamentals are sound.
They don't trust ATC completely. They don't need radios to fly safely.
When they assume the controls, the needles stop moving.
dtuuri