Hi Shay,
I've lived in Nyon for about a year and get highlights + cut about every 3-4months. I usually go to Llongueras (although my normal hairstylist left there and I was in a rush last time so I went to a place in the Signy center called Frank Provost.)
They are both pretty good, but don't speak english very well.
Nyon is much cheaper than Geneva, but if you get a BuyClub voucher go to Fifth Avenue in Geneva. They are super friendly, speak english and your hair always feels silky smooth afterwards :)
Not sure if that helped at all. Good luck though,
Isabelle