I know this is an old thread, but it came up when I was searching for something else, and I thought it was an interesting topic, so I read it through.
I was also puzzled as to what folks on the forum meant when they referred to a good "garden" daylily, but after reading here and participating for awhile, I absorbed a definition the way one does. To me a good garden daylily is one that has great growing habits: it's attractive, hardy, floriferous, unfussy, long-blooming, and clumps up quickly. Personally I would add "rust-resistant" to that list because where I live, that is a major factor in whether I enjoy a plant in my garden or not. So far, off the top of my head, good garden plants for me include Bitsy, Insider Trading, Going Bananas, Orange Velvet, Victorian Princess, Lemon Vista, Substantial Substance, Whatchamacallit, Chicago Apache, Caught Red-Handed, Reindeer Antlers, Cosmopolitan, Butterscotch Ruffles, Desert Flame, Dynamite Returns, Monica Marie, Frankly Scarlet, South Seas, Lullaby Baby, Novelty Number, Take Me Along, Willow Dean Smith. I am sure I will have more to add to this list after this season!
