Currently I am Cryo1>Linker1 soon to be rank3. From here I can branch into:
Cryo1>Linker2>Chrono3
Cryo1>Linker1>Thau1>Chrono3
Cryo1>Linker2>Thau3
Cryo1>Linker3>Thau2
Cryo3>Linker3
I suppose the regular Linker2>Chrono3 approach is the safer one, but considering the ammount of people going Cryo3>Chrono3, I could combo nicely with them by going Linker2>Thau3 or even Linker3>Cryo3/Thau2.
ps: I am aways duo-leveling with a Barbarian.
I think that link2->chrono3 (and link3 as r8 - as far as i know they are planning the next support class at rank 9 ) - is the best choice - your Barb friend will be very happy. And you can always find some thau3 friend to your pt 
I personally would still go linker2>chrono3. It’s unlikely you’ll be competing with cyro3>chrono3 all the time. However, if you think you’ll find yourself enjoying thau3 more, then there’s no harm going that way too.
Any Thau3 or Linker3 would like to share their experience?
To be honest, I’m a bit scared of all the negativity towards Linker2 and 3. Maybe I should reroll to the “meta” build Cryo3/Chrono3 
I’ve never seen a party that wasn’t thrilled to have a linker in the party. This spreadsheet has a pretty fair ranking of how good each circle is. I’ve gone wiz > pyro > linker2 > sorc2 so far, and I definitely find the additional links useful
I don’t actually have any experience with thau but if you like enlarging or shrinking stuff and the buffs that it gives, then you can go for it. Though you should know that the attributes will be expensive to invest in and with the fixed increase, the buffs may not scale well later on.
Linker3 won’t be the greatest thing to invest in since the only is more links and umbilical cord. You’ll have enough links with linker2 for most cases and umbilical cord in general is not that useful.
The negativity you’ve seen with linker may be because of the nerfs it’s had. Regardless, it’s still good to have in parties. Also don’t have the mentality that you should go for the most popular builds. It’s going to be more enjoyable to make something that’ll fit your playstyle.