Re: 45-70 being expensive... Factory ammo, yes, but reloads can be ver cheap. My practice ammo is a 340 gr bullet cast of wheelwright and tumble lubes over 13gr of Red Dot (known as "The Load" by C. E. Harris). This load comes close to replicating th velocity of the original 45-70 BP loading. Last time I figured it out, my cost was about $.065 a load. On top of the low cost, this load is extremely accurate in my Marlin 1895, shooting a ragged hole for five shots at 50 yds.
As for the list- I think the .270 should be in there in homage to Jack O'Conner, along with the previously mentioned .44 mag in honor of Elmer Keith.