Another vote for the
Walliserkanne. That's where we take all of our out-of-town business guests for traditional Swiss food.
For something slightly more up-market, I also like
Safran Zunft. It's quieter and a little more intimate.
Given the choice, I'd take a group of 4 or fewer to Safran Zunft, 5+ to Walliserkanne.
They're about a two-minute walk from one another, so you could check out both and make your choice.