That question, I'm afraid, is right up there with "Which came 1st, the chicken or the egg?" I don't know that there's a definitive answer for either question. Lots of people have spent lots of money designing/marketing/buying/using different designs. Unfortunately, the"perfect" feeder has yet to be made.
The best I can suggest is for you to visit a thread called "Show me your feeders" elsewhere on BYC. There are literally hundreds of homegrown designs, and at least that many more modifications of each of them. I chose what I felt was the best of the lot for my application and built it, secure in the knowledge that my wasted feed days were behind me. No such luck. I have less waste now than ever before, but I still have some. Fortunately, my birds are able to clean up most of what the slop out; I can live with that.