Help please teachers! Which union?

[pugsandseals]

I was reminded at INSET that I should really be a member of a teaching union which I hadn't even considered before!

So, which union do you use & why? There seems to be a huge amount of choice & I'm not quite sure where to start!

Was in the NUT but changed to NAS because of the local reps (not school ones, although they are important) also vast majority of the teachers in my school are NAS.

I've been a member of ATL since I started teaching (when they were AMMA). They were absolutely hopeless when I needed help recently. They didn't listen to what I was saying at all and I felt they sided with management. I'm not going to renew my current membership and will probably join NASUWT.