Depends on how much time, and money you have.
Tubs, and lick tanks are easy to use, least time consuming, but are expense.
Cubes take more time to feed, but are cheaper than licks, and available everywhere.
Meal is harder to feed, but is the cheapest on a $/lb/protein basis.
For me I don't use any premixed stuff and just go with a 24% protein mix made of corn, and some kind of high protein source, plus salt. Dirt cheap if you source it right, most flexible in how you can use it, but you do have to hand feed it.