your opinion? Sonus faber Serafino Tradition vs the Focal Sopra 3

Focal all day. 

Focal will most certainly be more detailed. Some hear may hear excessive brightness. System/room dependent. YMMV

SF will have a subjective "warm/romantic" personality compared. Have not heard Serafino  but MANY others, assuming it follows the SF "sound."

I like both presentations. Prefer SF aesthetic.

The Italians taught the French how to cook. They have an aesthetic sense that is hard to overcome. Sonus Faber all the way! Compare a Ferrari to a Citroen.   

+1 tablejockey on the house sounds (like him I don't know the specific models).

Critics may accuse Focal of boom-tizz, and accuse SF of being insufficiently resolved or even unexciting.

My taste runs to the musicality-warmth camp, not the detail-resolution camp, so I've enjoyed the SF I've heard (I came close to buying), and found Focal a little fatiguing.

If your tastes are clearly in one camp or the other, that might well predict a preference.

As per @tablejockey ‘s post 

You didn’t state your musical tastes. I think that will play a big part in which ones you would prefer. 

I can only speak to the Sopra 2 and Olympica Nova III but it might help.

Both are fine and I could own either. The Sopra needs subs for bass extension while I felt the bass depth was better on the Sonus Faber. Both are pretty flat sounding. The Sonus Faber has a slight dip (I mean slight) in the presents region and a slight rise in the treble at 10k (on axis) to my ear. Focal seems pretty flat to me.

I think the focal has a bit more detail across the board but hard to say as they were different systems. If both were offered for free I would take the focal and add subs. Without subs I would take the Sonus Faber.

I personally bought the Revel 228be (also needs subs) which plays right with the others for 1/2 the cost. The 228be is flatter than both on and off axis. Had stronger center imagine, seemed more detailed than the Olympica III but maybe a hair less than the Sopra. The Sopra seemed to have a bit more texture in the upper bass than the revels. Mids and highs seemed like a wash. If all were free I would take the Sopra over the Revel as it looks nicer and sound just a hair more alive. But and a big but these sound pretty close and the cost is not close at all depending on your country of course.