The first few times I had Culver's I was very underwhelmed for the very reason you mentioned. I decided to try again and just go standard butter burger instead of the deluxe, and it's been better every time. It doesn't make sense because the only difference is the toppings, but it's been true for me every time.

I'm near Wisconsin, so maybe there's something to that. What I like about Culver's is that they used to be the expensive option, but they seemingly haven't raised there prices like everyone else. It's reasonably priced for the quality imo.

I'm near a Freddy's, but both times I've gone they've completely fucked up my order, and it's more expensive than Culver's that's very near to it. Other than the more typically fast food like McDs, BK, etc... it's the only real option for a quick burger around me.

I do think their chicken is good too.

The butter is for the bun, i think. I really only like them because they have an edible vegetarian option.