The current reward is Alolan Grimer, of which I have about 50. It used to be Legendary Pokemon like Zapdos, Ho-Oh, or Regirock in these boxes, and even if we had those Pokemon, it was still worth it because Legendaries are special enough to warrant five minutes of effort each day. It’s like a Subway gift card: you do seven things and you get a free sandwich. We do have daily research tasks, with seven complete tasks - not even seven days in a row, but seven total - resulting in a special Pokemon for us to catch. The game does have an attempt at this, but it stopped trying a long time ago with it.