Hi Yvonne, and welcome to MySwissAlps!
There is only one way to know for sure: add up the full-fare cost of all trips you intend to do by train, bus, cable car and boat and compare the total cost of separate tickets with the cost of doing the same trips with the Swiss Travel Pass, Swiss Half Fare Card, Eurail Pass etc.
You can find fares for Switzerland in the Swiss Timetable.
It is important to be aware that the fare shown for any trip in the Swiss Timetable defaults to half fare, as most Swiss residents will have a Half-Fare travelcard which entitles them to this discount. Your calculations need to be based on full fares, which are double the default fare that comes up.
There is information and a spreadsheet here to help you:
www.myswissalps.com/tr ain/ticketspasses/prac tical/chooserailpass
As it seems you will be using quite a bit of mountain transport in Switzerland, a Swiss Travel Pass or Swiss Half Fare Card is likely to provide best value in Switzerland, as coverage with the Eurail Pass is limited on mountain routes.
A Eurail Pass might be worthwhile for Austria and Hungary, but you did not tell us how long you will be spending in those countries and how much train travelling you will do there, so it is impossible to say whether a pass or point-to-point tickets would be better.
In any case, if you definitely want the cheapest option, you will need to do the calculations as mentioned above. If you prefer convenience and flexibility, I would probably get an 8-day Swiss Travel Pass, plus a Eurail Pass for Austria and Hungary.