Most of my experience is with functional programming, and it's my preferred approach. I have worked with projects using an object oriented style, and I think they make a lot of sense if the app is well defined up-front and the team is skilled in the approach. However, the modern web frameworks lend themselves to a functional approach, and I find it has advantages in simpler testing, faster development and easier to diagnose performance issues. Overall, both can be used, it often comes down to whatever is right for a particular team.