What ever groups the best. I am partial to the AB but all will do fine.
Spend time shooting a bunch. Once you pick a factory load, buy 5-6 boxes of it and get comfortable shooting it over the summer. Then buy 3 more boxes and start adding challenges to your shots. Off hand, coming down on the rifle after running gassers behind the range, etc. All of these are directly applicable to elk hunting and making it part of the routine is probably more important than 1 vs. 2 MOA.
