The answer to the question "what is the best tungsten for aluminum tig welding?" has changed.
Back before TIG inverters were so popular, and older transformer tig welding machines were the norm... the answer was pure or zirconiated tungsten.
Pure tungsten balls nicely and so does zirconiated and a nice spherical tip can help with cleaning action and a stable arc at medium amperage ranges.
But the problem is neither pure or zirconiated are able to carry a lot of amperage without breaking down.
2% thoriated tungsten can carry more amperage than pure or zirconiated but the tip mis shapes easily and can spit tungsten in the weld.
The truth is that no single type of tungsten electrode is that absolute best for every application.
For example, if I welded aluminum most of the time and rarely welded over 1/8" thick aluminum, I might chose LaYZr tungsten from CK because it works very well on arc starts and mid range amperage.
But because I make welding videos, I am frequently switching back and forth from AC to DC ...from aluminum to carbon steel to stainless.
That is the main reason I personally use 2% lanthanated tungsten for aluminum as well as everything else.
I find that it makes life simpler to only have one type of tungsten in my tungsten drawer.