I've gone through AOPA, US Aviation Finance, and Dorr most recently.
Dorr had the lowest rate (4.65%) and down payment (15%) requirements while allowing a 20 year term. Additionally, their fee for everything ($695) was lowest and included the escrow and title search costs. Happy to make an introduction if you'd like.
I am in the business of non-aviation finance. If you can obtain the terms as described by Matt I would look into Dorr. All of the ingredients are reasonable including the fee.
