Some things that I look for in daylilies are fixed, but I also have yearly variances in colors or other traits that interest me. (Last year, for example, I went on a Huben dip buying binge, even though I had previously expunged most of the dips from my garden.) I can sometimes also be swayed (er, inspired) by a pretty picture accompanied by high praise.
The "Need" List:
polymerous tets (I started out with poly dips years and years ago, but nowadays I do my pollen dabbling with the tets)
scape height at least 30" (there is a little flexibility here, depending on the "whole package", but I also have a lower limit)
rust resistance (I refuse to spray fungicides; unfortunately there is still not a whole lot of reliable info available on this, especially for new intros)
other disease resistance
emo and cmo
respectable bud count
large (or larger) flower
opens flat to recurved
good substance
sunfastness (in reds and the rare purple)
Even if a plant exhibits all of the above, I won't take it if something about the flower face turns me off, or if I feel that I already have too many similar ones. There are certain color combinations which I cannot abide, regardless of whether or not the plant has every single one of my "Need" and "Want" traits. ("Want" includes things like fragrance and diamond dusting... I really want them, but it can be hard to find plants with such traits, and the plant must have (at least some of) the "Need" traits first.)
On the other hand, if the plant exhibits only SOME of the above "Need" traits, it may get purchased - especially if I think I can cross it against something with the missing traits, and/or it has some of the "Want" traits - so long as there are no "Deal Killer" traits.
Color-wise, what I buy varies year from year, with the only consistent colors being polychrome, near-white, clear pink, clear lavender. (Yet some years I add more melons, or go on a red binge, even though reds are not usually sunfast here. A few years ago I added several large yellow daylilies; they are always cheerful in the garden, but especially ML and Late.) I am not a big fan of eyes (and especially not eyed-and-edged), but I can be swayed, IF the colors are "right".
I don't much care regarding foliage habit (dormant or not), so long as the foliage is not upright, and the plant trait is not hard dormant. (I have to say, though, that I have a growing fondness for dormants, or SEv daylilies that act dormant, with bluer-toned foliage.)
The "Want" List:
rebloom (I like it when I can get it, but the rebloom has to be when the weather is still good, and other traits are more important to me than rebloom, due to shade)
shade tolerant * (my garden has a LOT of shade, and thus many daylilies that rebloomed at an older home of mine, do not in their current home)
diamond dusting
fragrance
arching foliage
blue-toned (blue-green) foliage
(* In that vein, it would be great if the database had info on shade tolerance - i.e. does the daylily bloom, rebloom, perform well in the shade?)
The "Deal Killers" (but some of this info you generally won't find in catalogues...):
mud
upright foliage
rust (and other disease) susceptibility
hated color combos (that, at least, you can generally determine from pics)
short scapes (I MIGHT go a bit shorter than 30" if most of the other traits look good and/or there is something compelling about the plant, but I will not go below 26", period)
Despite all of the "Need" and "Want" lists that I make, I can still be seduced into purchasing. I really have to step away from the Lily Auction (which for some reason I find harder to say "No" to, than hybridizer catalogs and websites).
