Outdoor plants:
For me it's...
Agastaches, also known as, Hyssop or Hummingbird Mint.
They're long blooming, low maintenance, beautiful, fragrant, attract Hummingbirds, Bees and/or Butterflies.
Most are perennial to zone 5 or 6.
Many new varieties being introduced over the years.
I agree with Daylilies and Echinaceas too.!