These are the most flexible and often best cards in their class, and will fit into pretty much any strategy or archetype
Exiling an instant or sorcery from your graveyard to later cast for free whenever an attraction is visited is strong
My verdict: Octillery is a quiet MVP unassuming, but wins you games with consistency
Maybe when it was released you could make a cool deck around it (it is also a Legendary) but these days Iname only lives in very few decks and probably is rarely actually cast even then
Meanwhile, Yennett, Cryptic Sovereign is one of the most interesting build-around commanders in the set, facilitating a brand-new archetype in odd-converted-mana-cost tribal (while still being fine on its own, with the double evasion making it pretty easy to draw an extra card each turn if you can't cast that card for free), while Varina, Lich Queen finally unites all of the colors of Zombies, so if you are looking to add the white Amonkhet Zombies to the blue Innistrad Zombies on the traditional black Zombie base, she's the best (and only on-tribe) option for your commander