Which would be the best pass

Hello Anand! Great that you get to make a tour through Italy, Austria and Switzerland. Only exact calculations will point out which pass or pass combination is best. But generally, such a 3 country pass is only worth its money if you plan to travel quite intensively in all three countries. If that's not the case, you might indeed be better off buying a 4 day Swiss Saver Pass or a 3 day Swiss Saver Flexi Pass for the Swiss part of your tour and regular tickets for the remaining countries. The Swiss Pass covers more transportation in Switzerland than the Eurail Pass does (please compare using through the Swiss Pass and Eurail Select Pass page). For example, the Eurail Select Pass doesn't cover all parts of scenic trains such as the Glacier Express. Moreover, the Eurail Pass is available in 1st class only, whereas the Swiss Pass and Swiss Flexi Pass offer a cheaper 2nd class variant too.

I hope this helps you decide!