The answer is buckets are the ideal size to grow just about anything that can be grown in a traditional garden from herbs to vegetables and even small fruit trees.  They are designed specifically for the human body to pick up and move.  They are stackable, durable, and best of all very inexpensive.  The only modification needed is to drill a 5/16″ hole 3.5″ up from the bottom of the bucket to allow excess water to drain.  Containers, especially those the size of a bucket, can be quite expensive and if you want more than a couple, it can be quite an investment and they still don’t address the watering issues.