wind master seems to be the most popular XD
I recommend saving some points for that new skill tree that is coming soon...

currently got 21 on spiritual, 26 on wind and 6 on mechanician
before i had 26 on spiritual and wind, but then i wanted to start on the mech tree to get master summoner cuz its after trying it once i found it was amazing for building Q.Q

Spiritual guide, very useful!

i'm a full level wind master with 2 bits of spirit guide

Windmaster is completed for me. I'm working on Spiritual, which I'm just about done with that. Then after that I'll build up my Mechanical tree.

My Mechanic tree was the first one I finished

Then I started on Windmaster

And I'm about half way up my Spiritual one

Well I have 30 Spiritual Guide, 26 Wind Master and 19 Mechanic so far.

Spiritual guide(first one i started on)- 32
Windmaster- 26
Mechanican - 7

I have 27 points in Wind Master and 24 in Mechanician. I only need the top skill of mech and then I am going to move on to spiritual guide.

I started wind when skills were first implemented. Personally I like it, obviously I use acrobat the most and the make a mouse kiss if you're nearby. But other than that I use mech for demolition and that's kind of it since the extra range is useless on divine. On spiritual i only use revive and easy vic

wind master & spiritual guide
dont mind the chat// those people are weird

I'm trying to use them all, and not use whatever isn't useful in the skill trees. Example: More icecubes, companion cube, superstar.
However the first one I ever got before I started that was Wind Master.