Cost of materials is roughly based on weight, but it's not really that simple. The estimation of rebar cost relies upon bar size, weight, handling and cutting issues, repetition, types of fabrication, and overall project size. Do not worry about which hook for pricing purposes. Design your building according to good practice.
Constructibility is the primary factor in getting the most economical building. The designed reinforcing should avoid conflicts and excessive congestion. The best designs usually use consistent joist, beam, slab, and column layout and schedules, without unnecessary complexity. Because of the way bars are bent and transported, avoid having similar members when identical ones will do. Do not try to work every extra pound of reinforcement or concrete out of members in the name of economy, unless you are working on a tall building where the weight adds up quickly as you move down the structure. If you want to get into it, consider the way bars will be assembled and placed to avoid making things more complicated than required.
Formwork labor and materials account for about half the cost of concrete construction, so consistent, modular formwork from level to level, and end to end within a level, generally minimizes costs.