RicMic,It looks to be it's just a matter of preference,the weatherby will come with a MOA guarantee,but either rifle will probably do it....the price of the weatherby will probably be less also....in either caliber,you're gonna experience a pretty good thump,it looks like the 300 WSM has slightly less recoil in simular weight guns (about 2-3 pounds less)then you hafta look at what the 2 guns weigh.obviously,the heavier,the less felt recoil....also, the 300WSM will be a short action,and the 300 WIN MAG will be a long action
Ultimately,it comes down to how each feels in YOUR hands,not what I like or anybody else likes.....weight,how well it fits you,smoothness of the action,trigger pull (the vangaurd is adjustable,i'm not sure about the winchester)
all that said,I'm gonna vote for a Tikka T3 lite
seriously,do hold one of these before you make up your mind,I LOVE mine,it shoots half inch groups and feels great in my hands and is very lightweight...also,the trigger has no creep and can be adjusted down to 2 pounds with an allen wrench and the bolt is silky smooth