Blueprint Prefabs and Nanite. Best Practices?

I want to build a larger level with lots of complex buildings and structures. I plan to use a lot of kitbashing and combined prefabs to create the buildings.

With Nanite, is it better to create kit bash’d buildings using blueprints and blueprint sub-structures (more flexible, but many draw calls) or should I collapse the prefabs into single static meshes (less flexible, but also less draw calls)?

What is the best practice under UE5.1 and why? Thanks in advance!