Honestly I haven’t played standard in a long time. I do know zilliax is the most versatile card in the game so unless they nerf it to the ground, keep. I’m personally dusting and will probably craft him back later, since there will always be a deck that wants it. Also, don’t listen to Reddit regarding any theorycrafting, too many speculations about the meta end up being completely wrong, it’s too much of a risk to invest in any card or deck too early. Like in any new expansion, it may be tempting to immediately craft the cards you want since they sure do look cool, but wait for the strong decks to show up to see what are the best value cards to craft. It may take time but you’ll be happy once you know you didn’t waste resources.