Graybeard and oldtimer make some fine points.But I must disagree with the if you are a handloader go for the 356Win and 307win.The 307Win is a good choice,with factory loads in 150gr and 180gr and handloads in 110gr,130gr,150gr,170gr and 180gr.308win bullets should only be used if they are round.The 356win is a better choice than the 375win if you don't handload.The 375win is a better choice if you do handload.It will do everything the 356win will do,with a larger diameter,better KO and heavier bullets for large game 255gr Barnes O.Here is the low down.
375Win handloads using AA1680 and IMR3031
200gr Sierra 2396fps,Accurate
220gr Hornady 2335fps,Accurate
255gr Barnes 2015fps,Conley
I am in the process of chronoing some more 200gr,220gr and 250gr bullets for the 356win.Using some different powders.But I have never gotten the velocities i got with the 375win.And never ever reached published loads for the 356Win,as they are always taken from 24in barrels.I have used H-322,H4198,IMR 4064,BL-C(2) and AA2015.If anybody has some different powders or has chronoed some loads from 356win.Lets hear them.I have gotten 2400fps with 200gr,2300fps with 220gr,and 2115fps with 250gr.
So the order of purchase would be for me,as a handloader.
375Win
307Win
356Win
444 Marlin