the 7x57 is king
you have different military 8 mm cartridges from 8x50R to 8x63 and there are also different 6,5 from 6,5x53R to 6,5x58 but there was allways one 7 mm.
there are wildcats based on different military rounds like 7x53R Mosin, 7x54 Mas, 7x54 Lapua/Swedish Mauser, 7mm -303 Brit
also a 7x56 carcano. everyone want to copy the 7x57 Mauser. with the years I became a strong believer in 7x57.
when talking with beginners my advise is - your first rifle should be a 308 Win.
and when you need another one buy a 7x57 rifle.