Even though some may indeed be better than others, it still sounds like none of them hold the number of birds advertised and all of them require additional work. Dogs are absolutely the worst land-based predator there is. They kill birds just for the fun of it and you definitely want something that they cannot break into, and having a perimeter to keep them away in the first place is a good idea. What dogs don't physically kill, they panic and cause to die, at any rate it's the same result...dead birds. I know that there are many wonderful, noble dogs out there but I'm honestly not fond of the species in general.