I was a member of ActivFitness for a year. It's a chain with locations randomly scattered all over Switzerland, and you can access any gym without any additional cost. Price-wise it's one of the cheaper chains, but the facilities were always clean and well maintained. An Abo for a year is around 750 CHF (if I remember correctly), which is a few hundred cheaper than MigroFit or ActiveFitness, for example.
I used the one in Oerlikon a few times. It's in the new UBS building, on the two top floors. Never too full, and a rather OK selection of machines. I'm sure you can do a test training for free the first time to see if it fits your personal program
I have nothing negative to say about ActivFitness and would still be using it but it doesn't make logistically sense anymore since I moved and no longer have one easily accessible between home and work.