For short films and some features, it is ok to produce a mix in stereo but in general, most of them will require a 5.1 or higher surround delivery. To determine which type is right for your film, you will need to know where the film is going to be played and which platforms for distribution you intend to submit to. Youtube for example, is stereo only while many distributors will ask for a set of 5.1 stems for your film before they will accept it for streaming.
In comparison to 5.1 surround sound, there are lots of other options to consider as well. There is 7.1 and immersive formats to include the likes of brands such as Dolby and DTS to name a few.
Surround sound has come a very long way especially in recent years and your film will greatly be improved if it is done correctly however it can be a tricky slope to climb when you consider the costs associated.
While you may be able to delivery a surround experience to your audience for home entertainment applications, it is common for indie-budget films to skip a theatrical release because of the expensive licensing that comes with commercial theatre screenings. This does not mean you are limited to less than you desire for your films sound format but it can definitely be a limitation in terms of where your film will be able to be shown. As far as cinema's are concerned, unless you do pay for the necessary licenses, you will only be able to show the film in cinema's via an unencoded DCP for the purpose of festival screenings. All other platforms online are able to take on a film without licensing and physical media only needs to be licensed for commercial use.
