These are 2 completely different plants and I would definatly go with the Lilium on this! The 'Kagari Bi' is a true lily (bulb).

The flore-pleno (also referred to as fulva or kwanzo, I forget which is which) is the double form of the commom 'ditch lily' and is a hemerocallis (daylily). If you wanted double daylilies, there are way better choices than this one.

The double lilium is gorgeous though!

Old House Gardens lists the heirloom, L. lancifolium/trigrinum 'Flore-Pleno.'

Here is a link that might be useful: Heirloom Double Tiger Lily

Sorry Butterflylion...When I saw "Flore Pleno", I immediatly thought of ditch lilies and didn't even know there was a true lily out there with the same name.

I have neither of these and grow mostly the orientals, but do have a few asiatics. Actually, the daylilies are my real love.... But I say you should try some of each of those!!! :)

wildflower, yes I would like to grow both and see how they compare.