Hi there, i am currently working on a mobile open world game which includes loads of buildings and bungalows. For bungalows, i just make it as a single static mesh and then import it in UE4 and for buildings i just make one floor, base and top of it and then add the rest of the floor in UE4 in Blueprint way as shown in this amazing video tutorial UE4: Good-Looking Randomization for Procedural Buildings - YouTube which allows me to add any static mesh on all the floors in a random way without placing each mesh in each floor separately. for instance and air conditioner. Now my question is, should i continue doing this as blueprint way or should i make the whole building for example of 10 floors and combine it in a single static mesh? which one between these two is better for performance of the game?
Well Tech Art Aid is using Houdini, (aside here Houdini for unreal is paid only, even the free version, I tried). So I followed this guys version here. I would be sure to use instance static mesh or hierarchical instanced static mesh if you plan to have the same building multiple times over. It is more efficient on memory, and these systems are made for faster rendering.
I recommend the HISM system, its has a few more features. now there is the new proxy LOD system, but that I believe is 4.19 and newer.
so you can do the vid below with HISM instead of the regular ISM, if im correct the ISM don’t do something the HISM version does. and you will be up and running.
Well i am Not really reusing much buildings, yes in some places i duplicate the same building and apply a different colour to it. My concern is weather to use blueprint way as you mentioned here UE4 - Constructing Buildings with Instanced Static Meshes [TUTORIAL] - YouTube or just place static meshes for each building?
Well it does more than just make things easier. using this you can: have dynamic material instances, dynamic parts, and dynamic collision. This can be at compile time or runtime. you gain a lot of features doing this, and you also can make it procedural when you put some more work into it.
well i think i must try to make it procedural thank for your suggestion 
cool, did I help any?