Well as far as I know most math forums on the internet are not so active , in particular when its not about homework and integrals.
My opinions are subjective.
But if you can find me another math forum that talks about tetration alot with over 6500 Posts , i would be surprised.
And even if you find free stuff about tetration on say wiki , math stackexchange , mathoverflow or forums , it is USUALLY related to the top posters here ( or their Friends / students. For instance my friend mick on mathstackexchange. - tag tetration ! - ).
So it is relatively active in a way.
The subject of tetration is not so popular in math.
Although complex dynamics , dynamical systems , fractals ... And other related fields are gaining popularity.
There is no shortcut in math , but Some threaths have much more views and replies then others.
I think that is a good way to start.
Also , the open problems survey is essential imho.
Compositions and limits are imho essential for the majority of posts in the last 4 years.
Complex analysis is a must too.
At the moment 28 nov 2015 , i classify the contributors according to the ln of their posts , on a scale to 10. Im sorry if that is offensive too Some.
For the last 5 years , i am - and i assume gottfried too - desperately looking for ways to understand infinite matrices.
You Will notice the words uniqueness , existance , analytic and equivalent turn Up ALL the time. That is no coincidence.
Hope that helped.
@Gottfried Im sorry to hear you are still sick. Im sick too , and i find it funny that 2 sick people post so much here.
So many problems and still looking for more

Im getting better and I hope you too.
In either case you have become a tetration legend.
I hope your website Will exist forever.
Take care buddy.
Regards
Tommy1729