I think the types of loans are quite good. I think one type of loan is missing. One where you get payed out not 100%. I think a loan with a disagio is missing.
The advantage of a loan with a disagio could be, that there is no interest rate during the whole time of loaning the money and the interest is calculated into the disagio that it corresponds a certain % of the whole sum of the loan. Than you have only to think to pay back and have enough money on your account a couple of days in front of your main repay date and not every week.
I did not think about negative Interest. But in real life you usually get a loan where the first 2-3 years just for your interestrate, but after this you begin with a downpayment. I think this could be very interesting here, as in the beginning you make no great profit with a new base … it takes 2-3 weeks till everything works fine. So a loan which has a downpayment is gerat but not from the first week on. The second one I tought about was a loan where the interest ist included in the last payment or in front of the payment. You dont get 100% but only 80% or whatever. The rest is the interst rate payed in front.
Decreasing Interest: Paying your interest payments backwards - more expensive payments first.
Negative Interest: Paying less over all payments then you originally received, with more expensive payments first.
Positive Interest: Paying more over all payments then you originally received,
with less expensive payments first.