Royal Standard. Plantaginea has flowers that are at least twice the size of those in your photo.

And fragrance level to match flower bud size

So, the next question is which hosta would you choose if you wanted this large August bloom with an all-green leaf? Planted in a massing of 15 to 30 plants.

Honeybells is fastest grower, followed by Royal Standard and plantaginea slowest to grow and bloom

Depends on your light levels. Plantaginea will grow at a reasonably good rate and bloom more profusely if it's given a lot of sun. Honeybells and Royal Standard will grow nicely in a lot of shade. My favorite fragrant bloomer is Fried Bananas, it will take full sun to half shade and still bloom well, but it's not green, it's considered a gold. I consider it a chartreusey sort of a soft green, with a nice glossy leaf and it looks good all season. For some reason, the hummingbirds in my garden always zero in on FB first, and visit every single flower before they move on to other varieties.

Looks like Royal Standard to me too. Best smell ever!