I recommend setting the max price you are willing to pay for a box and buy one of everything that costs that or less,I would keep my choices to the ones you can easily get locally...I like Federal,Hornady, and Remington myself...the actual weight depends on the game your going after...for medium sized game I would probaly use 140gr. for the .270 win...there are quite a few bullet types available from all manufacturers so be sure to try as many as possible...be sure to clean the rifle between ammo types.
After you determine your rifles favorite load, zero it and shoot the rest of the stuff to get used to the trigger and recoil.
I have shot Remington CORE-LOKTs for years, but here recently I have been using Federal Premium Nosler Solid Base, I am happy with both of these for Whitetail and both shoot very well for me.For the record the Federal Premiums hold a more "consistent" grouping in my rifle.
Remington Premier Accutip Boat Tail shoots good out of my Ruger M77 7mag