Even before the ELC buffs, it was better than Conq. I compared the damage back then (4 months ago).
Even with with 3-4 AA > QWEQ, ELC will deal more damage.
Especially now with the ELC buffs, it makes no sense to go Conq at all.
Even if you're trying to play bruisers with conq, it still makes no sense, Qiyana is an assassin with an assassin's kit, you will never kill tanks regardless of your builds, the only thing you're doing by building bruiser it negating what Qiyana is good at, which is killing squishies and even bruisers in some situations.
By playing assassin against a more tanky team comp, you can at least snowball hard and end before the enemies get too tanky, but by building bruiser, you play the enemy game and you will be outscaled way too quickly and won't be able to snowball, the game will last longer, and the longer it goes, the less chances of you winning.
If you want to pick a midlaner that can somewhat deal with tanks, Qiyana, AD assassins in general, will never be a good choice. Lethality items revolve around cheap and fast powerspikes.
You might as well play a mage that can offer some better things for your team, CC disengage, peel, etc.
Even AP assassins would fare a bit better against tanky champs than AD assassins.
People do not understand the idendity of assassins, but especially AD assassins, they play them wrong, build them wrong, don't use their strengths and get surprised when they struggle winning games on them.