I was a Quicken user for nearly as long as the OP, but also will not pay for a subscription. When i bought a new computer I switched to Ubuntu, was really sick of Microsoft wanting to know what I had for breakfast. The problem with Ubuntu is that most of the programmes are double entry bookkeeping, unlike a Quicken Cashbook. There are Windows programs that are single entry cashbook style but finding one that has the detailed reports in Quicken is the problem. Unless you are an Excel expert you would have the same problem.
For Ubuntu I now use MMEX Money Manager but as stated it does not have the reporting capabilities,