Arctic Silver 5 no longer king?

Back in 2008, I remember AS5 was considered one of the end-all-be-all of TIMs, but it seems that has changed.

I've seen PK-3, Coollaboratory Liquid Ultra and Pro and IC Diamond. Am I missing any?

It seems like PK-3 shouldn't be too much different than AS5 - but it would be better as aluminum outperforms silver (which outperforms gold) when it comes to conductivity.

I'm wary about Coollaboratory's offerings, as I am familiar with the chemistry of gallium, aluminum and silicon. Specifically, Gallium is "electron-deficient" - yet cannot strongly hold electrons that it comes in contact with. It is so deficient that it will bond to other conductors and semi-conductors that are already normally considered "electron-deficient". They've been using gallium arsenide for years to cut silicon in CPUs to increase it's performance (increasing the "distance" between the electron-charges in p-type and n-type conductors, thus allowing the gates of transistors to operate at greater frequencies).
If it wasn't for the layer of copper in most IHSs, I would flat out refuse to use Coollab's thermal pastes.
I'll ignore the fact the Gallium is not only conductive, but capacitive.

As for IC Diamond's paste, I'm not crazy about having to put any of my boards into an oven, like I've read that so many people who use IC Diamond have to do (on top of the pre-heating it in hot water).

What are everyone's thoughts? Do any one of these TIMs outperform AS5 so greatly that it out-weighs their inherent hassles/risks?

I mean, the diamond does make sense. It has the highest naturally occurring conductivity of any material we've ever discovered. something crazy high like 2,200 kw/m - copper and aluminum are only around 400 kw/m. The only other materials that beat Diamond are Graphene sheets and Carbon Nanotubes.
Fun fact: Carbon nanotubes exhibit something called "Ballistic conductance", meaning heat travels down, along their axis, faster than it should. Near instantly. At the same time, Carbon Nanotubes have about the same conductance as dirt (literally) with heat traveling across their axis. They are both great conductors and insulators, at the same time. Now, it only you could stand a bunch on their ends between your CPU and heat sink... (without baking your CPU inside a several-thousand-degress oven filled with corrosive gases)

I suppose if you look at it that way. Just be ready to never get the heat sink or water block off. I know they show the video of "removing it in seconds", but I suspect it was filmed immediately after applying it, and it counts on you being able to get the heat sink detached in the first place. I you know you will never be taking the heat sink or water block off, go for it - just be sure you don't get any on the "sides" of the IHS, or be sure that the copper in the IHS goes down the "sides" (before being covered in aluminum) as well - and that the IHS has copper in it in the first place. It would suck if your CPU shorted out after a few years simply because the Coollab's liquid finally made it through to the circuity.

The only way I can see getting it off... I don't know... a lot of paitence, a heat gun and some isopropyl applied to the joint between the CPU and heat sink, a little at a time?