Start from client workflows
Describe how a typical client in your niche runs money through the business. Where does revenue come from, and how is it recorded? What are the main cost categories? Which reports do owners ask for, and how often? Write this as a short narrative rather than a feature list.
That narrative becomes your test script. Walk through it in any software you evaluate, using realistic sample data. Gaps show up quickly when you try to follow a real client’s month, far more reliably than when you tick features on a comparison sheet.