I can recommend Winni's SalsaPassion school. It is near HB in Zurich: http://www.salsapassion.ch/e_workshop.html
She is Japanese teacher, speaking German and English (funny pronunciation), but she is very friendly and fun. I was doing 4-5 months of dancing (I am in the mid-proficiency level).
Also a friend of mine was going to Salsarica in the city centre, I have personally haven't tried it. It is a little bit cheaper than Winni. What i like about Winni's approach is that you change a partner every 10 minutes, so you will be dancing with many partners and understand better the feeling of the dance from it.