A smooth mathematical algorithm will suggest, without fail, that earning 3% is utterly foolish compared to paying 18%. For this reason, without other considerations, the solution will ALWAYS be:
A) Maximum Payments on the Highest Credit Rate
B) Minimum Payments on everything else.
If you have an Earning Rate higher than a Credit Rate, then the problem gets interesting. As long as your Earning Rate is lower than ALL your Credit Rates, there is no confusion.
Having said that, the concept of NO savings generally is considered socially unacceptable. Defining a minimum payment for the savings account will solve this social problem.
Note: Loans can be tricky. You must read the terms very carefully. There may be punitive clauses for early payment. Car loans are notorious for using the "Rule of 78s". This packs interest into the beginning of the loan and you may not calculate it correctly.
Note: Credit Cards can be tricky. Transferring balalces at a tempting interest rate, maybe 1.5% is likely to be a surprise. 1) There probably is a fee to do this. Accounting for future interest costs against this fee is non-trivial. 2) If you pay more than the minimum, the additional amount probably will be allocated to the lowest interest rate portion of the balance. This is NOT what is wanted by the consumer.
Note: Unless you have a really stupid mortgage, such as one that increases for quite a while (negative amortization) or simply never decreases (interest only payments), mortgages tend to behave rather well, but keep your eyes on escrow charges. Do NOT assume the bank has a clue. Prove it!