Primarily oats. Typically add some fryer grease and/or molasses to the area to help bring them in. Leaving some on the ground in front of the bait station can also be helpful - bears will track the scent through the woods and perhaps draw in other bears that cut those tracks.
Idaho, I have always used oats with molasses not the whole oats only the cracked oats. Also put grease outside the barrel for additional scent. I always use a barrel due to the spring weather and the birds. Mann those birds can eat just as much as those bears. A 50 gal barrel will hold 250lbs of grain. Good luck this spring!
Btw the molasses is the 5 gallon bucket for cattle we get at the feed store, much cheaper.
Alaska. I always use El Cheapo dog food. Restaurant grease on the logs and some maple syrup to sweeten it up. If I think of it, I drop a bit of anise oil around. While on site I like to burn some honey or jello.
Won't be throwing out any old fish heads again. We had big brownies all over the place. It is exciting to drop a pine cone on that big square head and watch the muscles ripple.
In Wisconsin for black bears, I use oats, corn and donuts covered with molasses or liquid smoke to start. That usually gets them coming in, and if they slow down right before the season due to the acorn crop or other mast, I switch to dog food covered with Cameron Haynes "bear crack" recipe (Marshmallows, powdered Jell-O, syrup & sugar). It hasn't failed me yet...
Dog food, popcorn, old produce from the local grocery stores and old kitchen grease from restaurant fryers works great! Just got mine out Sunday and come to find out there are two Grizzly in the area.
Check out "bear sucker" on line...I think for keeping a bear around this is going to work great!
We use carp and rotten poultry to create a good stink in a black plastic sack about 20' off the ground on a string with a few holes to allow a LITTLE scent out (a little goes a long way). A few small pinholes in the bottom lets the juices drip a little when it heats up on warm days. You don't want it to dry out or it will quit stinkin'. You also don't want the stink close to your stand for obvious reasons - just close enough so the bears will easily find the bait when they investigate the stench. For bait we run bread and tortilla products, grease, oats, frosting and cake stuff from bakeries, and the secret ingredient is a candy bar center that is maple flavored marshmallow - smells so good you almost want to taste it yourself. We get that from the manufacturer - off spec product they otherwise toss. A buddy from out of state scored that hook up - it's the best bait we have used.
I've heard that liquid smoke as someone mentioned is also a very good attractant. We drizzle grease everywhere so they will track that around the woods on their feet. I think it also helps other bears find the baitsite. We ran some bait in yesterday to one site we've used for 20 years. There were fresh bear tracks and scat there already. They must be ready for feeding time.