While a self tour allows you the liberty to spare enough time to every attraction, a guided tour involves the company of a skilled tour guide that will brief you to local bytes and facts of Switzerland. A guided tour also involves the security of groups, and allows you to socialise with other travellers with safety. A guided tour often also involves several perks and added ancillaries to make your tour a memorable one. Apart from this, you may also put your worries to rest about travel and food apart from comfort — all of which goes hand in hand with your ticket.
That said, a guided tour is not for everyone- waking up a certain hour, mingling with other tour group members, and following a perfectly-charted out itinerary for instance- is not everyone's cup of tea! So choose according to your fancy.