What is the best platform to combine data presented as either 2D or 3D+ in?

Now, don’t bother trying to talk me out of the question or prove it to me why it is bad practice to combine 2D and 3D in the first place.

Let’s just assume that it is a valid question and that I have numerous and totally legitimate reasons to regularly combine 2D and 3D+ data into one, digital place.

I like bringing 2D drawings (in fact that is what they are) into an accurately defined 3D space where I then model over.

I combine these with ready-made objects, often originated in non-AEC native authoring packages and I like to keep their intelligence intact.

When you decide to advice me, take the question to its limits at both extremes and include PDFs, not just ones created in CAD applications but also scanned-in sketches and on the other end, meta-data laden, heavy, 3D+ intelligent objects.

Also, allow me to have the ability to place the 2D stuff (sheets) onto any plane within the space, horizontal, vertical, under an angle.

I hope to create a meaningful discussion on this subject with pros and cons for various existing platforms.

Subjective comments are welcome, also real quantified observations (for example ‘xx works well until you load up 10 x 2D sheets and then it becomes really sluggish’).

Am really looking forward to great ideas – though not quite holding my breath!