No need for a magum or the cost of magnum ammo for deer in my opinion. There are plenty of smaller caliber cartridges that provide plenty of velocity/power for deerat longer ranges than most hunters couldever accuratly shoot.Having an accurate MOA rifle is far more critical than power (especially)for deer.
I assume you are in open country, the 270 win is at the top of my list and provides 3000+ fps factory loads.Ammo is 30% less than any of the magnum ammo when comparable bullets are used. The short action 243 and 7mm08 are great choices if alight weight rifle is important.

It makes no difference what you use as long as it's a 270 or 280 or 6.5x55 or 308. There are many other good ones but over many years I have dropped about 350 Mule deer with those four calibers. As a kid I killed quite a few them with a 22 LR.