about me: I'm 24 years old and recently switched companies.

Company A: I do now work for a medical mid-sized company, with a old IT and old structures in a boring job but I do get paid good. 3343 monthly for 37,5 hours a week, with 31 days paid vacation. Working here does not benefit my knowledge that much. (I have the option, to learn while I work, as I have some spare-time between tasks.)

Company B: I got an offer from another start-up like company, with a very interesting job, doing what I like. They pay: 3000 monthly for 40 hours a week, with 30 days paid vacation. Working here, would benefit my knowledge for my future plan greatly. I would not have that much spare-time between tasks.

Future plan: I am in the progress to start my own SaaS, this is why the question is tough to me. I am able to write code and host servers, I do not need to learn much, to start the SaaS but still, I do not know, if I should take the offer or not. I really tend to do so, because I think it is better for my future. -------

Can you give me advice in my choosing?