I like the 3-gallon bags but they need a few more drain holes imo.

The good thing about them is you can shape them and if you think the roots are getting bound you can smush the bag to losen up the root ball and the dirt. (not to the point that you damage the roots). You can't do that with a pot or 5 gallon bucket.

The smaller the bag the smaller the root ball will be and the smaller the yield will be as well. fyi