start with brute force (just draw them all), and if its not fast enough switch to hardware instancing, unless you already know brute force won't be fast enough.

I'm in the same situation you are. As an example, I use cubes. I gather all vertices and indices from each cube and store them into a SINGLE vertex buffer. Doing this will help a lot with frame rate. I wouldn't use hardware instancing if you're going to be updating the objects frequently, but I'm only saying that based on my project. I don't know what kind of shapes you're using so it could be helpful. I've never used hardware instancing so don't take my word for it. In my opinion, storing everything in a single buffer is the way to go

And as Norman said, brute force could work best for you. If objects go outside the screen, just remove them. Drawing each object individually would give you easier control over how each object is interacted with, but too many objects will kill your FPS. I had 30,000 vertices with 55-60 FPS. It all depends on how many objects you draw.