Well, to be honest here, the Remington 700 is the most prominate, and easiest to build on, rifle action. It's very easy on tooling and there are a ton of drop in parts that don't require a hell of a lot of skill to "custom fit" - so it's going to be much more common than finding a 'smith who builds on pre-'64 Winchesters.
That doesn't make it bad, but it also doesn't make it the best thing going.
Remington's new action, the one submitted to the military for their Sniper Platform Testing, is supposed to be AWESOME though - and if they win the contract, that might be THE long action to get in the coming years ( from a production rifle standpoint ). Rumor has it that if the Long Action takes off, Remington will spend the money to re-tool and offer a short action in the same design mode. If they do that, Remington will have "factory action" bragging rights.
JD