Friendly, helpful staff. No nonsense. No pressure when I told the agent I had already purchased insurance. There are weird laws about EU citizens driving Swiss cars into the EU -for which I think they may want to charge you more and give you an EU car - but fortunately that didn't apply to me with my US license. I had a horrific, straight up fraud experience renting from Sixt at Ljubiana airport in 2014 and swore I'd never use the company again. Friends in Bern insisted Sixt in Switzerland was good and I tried the company out again. I was glad to see they were right.
I'd never driven a Renault before and had no opinion about the brand going in. Now, I can say I'd never buy one. The automatic transmission is poorly designed, the shut off switch that stops the engine at traffic lights functioned far from optimally, USB charging was a joke, and the navigation is very slow to load. This is all not Sixt's fault, other than that they chose to buy cars of that brand