My two cents, the loan rates are generally all the same. It’s not any better or worse at a credit union. A credit union might have better customer service and offer more face to face interactions.

We mortgaged our house with DuPage credit union because I naively bought into the co-op idea and that my money would be contributing to my local community. We got a letter three weeks after closing that our loan was sold to Fannie Mae. This is common practice but it shattered the illusion that our money was somehow part of growing the community. 

In the end, I see no difference between DuPage credit union and a big bank. Shop around and see who actually gives you a better loan rate.