For me, there are two that come to mind with a long action.
First, simple, easy, 25-06. Hard to beat in factory chambering. Easy to load, and shoot. I have one in the making on a VZ24 right now. It is a cheap Adams and Bennett barrel and a friend gave me a laminate thumbhole he built for doing some work for him. Should be good to go with 100s or 115-120s.
Second, 6.5-06AI. I have one on a 700, 28" varmint contour, B&C M40 stock. Shoots 100btips at 3500 and 123 A-max at 3200.

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This one is lots of fun.


I think, therefore I am, conservative.