GA provides a revive, which was left out of your calculations entirely.

If you really want to do this fairly, compare switching GA for an MBR. You could even add Youmuu's instead of Zerk's.

You explored one double PD build out of possibly half a dozen others. You're far from finished.

GA doesn't factor in because after killing you once in a 1v1, i'll just kill you again. You won't rev with enough health to kill me. 56% more damage.

You gave me a build, and I beat it. Is there some particular reason that you didn't tell me the 'best' one first, if there is a better one? Replacing zerks with YG doesn't help you either, because I could just do the same thing. And still do more damage. The build I used to beat yours is not the best, either. I intentionally excluded using malady/wits/MoM because they have variable stats. I don't feel like calculating the damage for each attack independantly. Those items would give a bit more damage superiority, but I'm too lazy to calculate when MoM shield and how much bonus AD would kick in.

I didn't state the build I thought was best because I assumed we were working within a realistic setting where money and the course of a real game was something of an issue (MB/IE/PD was noted in Gustaff's article but was not included because it costs significantly more than IE/PD/PD, therefor it wasn't considered a fair comparison). You managed to get around it by substituting GA for the ultimate economist's offensive item, Atma's, which is cheaper and combined with Madred's gives the same armor as GA.

IMO Atmas is not viable replacement for GA, because the revive of GA is overpowered in any realistic scenario where your team is involved. GA is an insurance option for real life, because we assume something is going to go wrong.

MB+IE+PD+PD+BT+Zerks vs the build you presented is a comparison between 1.5% HP to AD (about 29 with Kog's base health) and some armor vs 12% more crit, 55% more base attack speed, and 12% more movespeed. The movespeed is not involved with DPS, but the power of more mobility and kiting is again something we appreciate in real game-play. Aside from that, at this point both builds look nearly identical in terms of raw DPS. Since you don't want to involve the inconsistent variables assigned by Malady/WE/MoM, we can pretty much leave the argument at this and get on with our lives, despite me being able to argue that you could also fit those same items in a double PD build with IE and Madred's if we removed Berserker's Greaves in a totally non-realistic scenario.

The moral is, both our initial arguments were wrong. Your build isn't better, and mine isn't better. If anything they're almost the same. Your build benefits Kog's ultimate more, while mine is better for BaB. You build has a small amount more poke and burst, mine has a little more kite and dps. I don't really care about differences these small, and neither should you.

I really don't think that Kog Maw is the best example for this argument. To my knowledge, AP Kog is far superior to AD Kog in damage output, and AP Kog benefits more from AS and on-hits like Wits End and Malady. Any chance I could see some math on that? I think the build I generally see on my friend's Vayne is 2 PDs, a BT, IE, Zerkers, and I forget what his other item is. It might be a Black Cleaver, or it could be a second BT. And he essentially destroys whole teams by himself at the point where he gets that fed.

AP Kog is just another animal entirely. I have no doubt it's still the highest short term dps, bar none, in the whole game. AP Kog can literally 2-shot you with a couple autos and a full Lich Bane build. It's just not as easy to do now because of the nerfs.

It's probably the only example other than Cassiopeia of an AP carry being able to do more raw single target dps than an AD carry over an extended period.

PD give you the most AS, %Crit, %MS in the game. Best for 3 stats. Its less than 3000 gold. PD is super strong no doubt.

PD is pretty strong, but the second one is only really good on ADC if no one gets armor.

IE 2PD gives you the most damage vs no low armor
IE PD LW gives you the most damage after they buy some armor.

IE 2PD LW gives you the best damage in the game with 4 items. This allow for 2 more item slots. 1 for boots and the other usually for a defensive item or life-steal, but not both. This is the major tradeoff.

In my opinion you pay dearly for getting the second PD, but there are circumstances when its worth it.

The problem isn't two Phantom Dancers, the problem is the first one.