First let me say Welcome to the board X Commercial Fisherman. As to your three choices you have probably picked the three most popular guns used for deer and they all work fine .If you intend to shoot factory ammo I would suggest the 270 win or the 30-06 unless you want to buy the premium ammo for the 7 mm mag . In my opinion they don't use a hard enough bullet for for the extra speed of the 7mm Mag in the cheaper rounds . Other than that they will all work great on deer . Good Luck with your choice.