I am writing my first novel but cannot decide if its best to write a trilogy or a single novel. The genre is mystery, new-age, suspense with a bit of fantasy. The foundational theme of the story allows for additional divergent stories to be told and developed so I'm thinking a novel with future tales in future but on the other hand, the single novel is a big story with many subplots that could be turned into an exciting trilogy, creating anticipation for readers. (The best example of this is probably how Great Expectations was originally written by Dickens). I know that there is no wrong or right answer but I am looking for a subjective answer as to the pros and cons of both. Thanks in advance.
It could help to just start writing and see how ti feels. Sometimes stories 'wear out' and you realise it's only going to be one novel. if halfway through the book you realise you still have 90% of the story left to tell, write more - as long as each book has its own conclusion of sorts.
(i have never written a trilogy, however - so all thoughts come with a grain of salt)