I'd start with what you want arrival day to look like. That's usually a better way of choosing than comparing ticket prices alone.
What happens when you land?
A day sailing can be very convenient if it leaves you enough time to reach your accommodation before dark. An overnight crossing may be better when it replaces a long drive, provided you arrive rested.
Put all the costs together
Don't compare only the headline fares. Add a cabin if you need one, a hotel if you'd otherwise stop overnight, and the fuel and driving time for each route. Sometimes the dearer ticket is the more comfortable choice.
Choose for everyone in the vehicle
A timetable that suits a solo driver may be miserable with small children or a dog. Think about mealtimes, sleep and comfort as well as the route itself.
Routes to compare
A few things you might be wondering
Are overnight ferries always longer?
No. Compare the exact sailing.
Does overnight include a cabin?
No. Cabin availability and pricing vary.