Hearthpwn

So Zillax is nifty, I get it. He fits in any mech decks and is quite flexible.

Then there's Dr. Boom. I'm sorry, but he seems so fun compared to almost everything, really. 

Which should I craft? Zillax or Dr. Boom?

Dr. Boom I prefer more fun cards imo. You could also discover zilliax from his hero power so :P

Ziliax is more competitive than Boom at the moment. Only you can answer the question of what you prefer. Personally I crafted Dr. Boom because he was fun and he is fun, sadly lots of match ups on ladder don't feel good for warrior.

I have both and Zilliax is in more decks.

If you are a warrior main then Dr. Boom but if you play with multiple classes then Zillax. Both are good and both will see play in one way or another.

They're both solid.

Dr. Boom is central to the decks he's used in. But Zilliax has more applications across all the classes (obviously, being neutral).

I've been playing Odd Control Warrior with a pretty bloated 5-mana area. Currently going with 2x Brawl, 2x Dyn-o-matic, 1x Zilliax, 1x Supercollider and 1x Giggling Inventor.

I have considered replacing Zilliax for another Giggling Inventor. I don't think you can go wrong either way, it comes down to preference.

It depends how invested you are into Warrior. You can play a Mech Control Warrior without Zilliax, but you're probably not going to play a Mech Control Warrior without Dr. Boom, Mad Genius.

Boom is a fun card, and if you can get rolling with him, reasonably competitive. Plus, if you playOmega Assembly on 10, maybe you'll snag a free Zilliax anyway :)

It is still too early to really tell. But so far Zilex is looking good and dr boom is too slow. 

Zilliax, if you asking then don't have plenty of dust, so, craft the more versatile card.

I would choose Zilliax, it's s more versatile card.

Also, I would just dust a bunch of trash rare cards you'll never use and see if you have enough to make another legendary. I often find I only need to get rid of half of mine after opening packs at the start of the expansion. 

Dr. Boom is harder to replace than Ziliax immediatley, but the choice is yours. I opened Ziliax and Dr. Boom was my first craft.

Zilliax is a lower risk craft since it can fit into aggro, midrange, control, and combo while Boom has the potential to get pushed out of more lists in the off-chance that the meta does become more aggro oriented. However, I do agree that Boom is a card that is more fun imo.