It will depend some what on where you live and the type of soil you have. Most states have done surveys for best food plot mixes, or rather ,recommended ones. I dont think you can go wrong with oats, deer almost every where will feed on them. If you have enough land, several plots may prove effective, one in annuals ( oats and most grains) and one in perennials ( alfalfa, clovers)
I like clovers and alfalfa since they have a decent protein % and fix their own nitrogen (legumes) but growing them here in Texas is a challenge because of heat, I have had good luck with Dryland/Ladack alfalfa developed by Texas A&M I believe.
I haven't had much success with Rye, deer will eat them, but it isn't on their "high" list. I have grown Lab-Lab, it is an aggressive legume, expensive and you probably want to plant it with something like corn or milo that has a tall stalk, my lab lab climbed up to 8'!
I usually grow a winter plot (75% oats 25% wheat- sometimes a bit of arrow leaf clover) then in Spring plow and plant a summer crop such as some type of bean.