It is difficult to answer to what is the ultimate but to me the action must be of ultimate reliability, being able to cycle with
reliably within less than perfect hunting conditions like extreme cold and hot, snow and rain and not get jammed by a blade of grass or a pine needle, at the end of the day the Pre 64 M70 Winchester is my first choice followed by the New Classics with the older trigger system, third and perhaps it could even be first would be a modern CRF action that maintains the CRF system with a 3 position safety, the feeding could be a traditional staggered internal magazine or even clip fed if fed in-line like the newer Tikka mag systems, hard to improve on the M98 type system at the end of the day, Dakota did a hell of a job creating a modern pre64 in both the 76 (pre 64) and 97 (rem foot print) type actions with some innovative features, too bad Remington took them over and went bankrupt. If it is for anything less than big game hunting like varmint hunting then any action will do (and I do use many non CRF actions) .
BB