How to lose engaged colleagues and make some others just look less alive

What is most important, the tech stack, the company, the product or the team you are working in? I used to have the order: the company, the product, the team, the tech stack. Then I joined what I thought would be the work place of my dreams - and this order changed.

Why is the team and work place culture important? And what should you do to improve it? And what should you not do if you want to have happy and creative colleagues?