Microservices are very popular nowadays, but it would be a mistake to use them just because other people have adopted microservice. There have been many situations where companies tried to adopt the microservice architecture, but due to a lack of knowledge, they ended up creating something that was neither a microservice nor a monolithic application. They have not properly encapsulated services, and one service was connected to another so that one agile team could make an independent decision on deploying a microservice.
Therefore, it is good to start with monolithic applications, especially if you do not have any microservices experience. Also, if you are at the founding stage and have a team of five people or less, you should stick with the monolithic architecture because you will not handle the high overhead of microservices. If you are developing a new product that is unproven on the market, the chances are that it will evolve, so the monoliths would be well suited for you since it allows for fast product iterations.
The microservices architecture will be a good fit if you need fast and independent service delivery. However, you should know that it might not see gains in delivering your service right away. Also, if a particular part of your platform needs to be more efficient than others, microservices will be ideal because it allows for independent scalability and increased flexibility.