Kanta No.1 vs Olympica Nova 1?

This speakers are so different that I would really work hard to demo both before spending the money.  The Focal tweeters are often a love them/hate them thing for many folks and the Sonus Faber are (historically) a completely different and sometimes "warmer" sound.  What are you going to drive them with?  I think that would really be important in selecting one over the other.

have demoed the Olympica III and Nova 3 a few times. I own the Revel 228be and use subs which is important I think. 
 

The short version is I think the Revels are a better speaker. 
 

The long version… the Sonus Fabers have a slight dip in the upper mids. 2-3 db in the 2-3k range but I think the highs are a bit more tipped up at 10k compared to the revels. The Sonus Fabers also have a bit rounder bass with a bit of upper bass bloom. 
 

I have not heard the Kanta so I can’t comment but based on their measurements they are a touch bright. Depending on your age (upper hearing) it could be a good or bad thing. 

Personally I would not by focal or Sonus Faber as a second set of speakers to revel. They are both a step down in absolutes and just different. You might like different better though.  If I were going to try something different I would try open baffle or horns for a major change. 

I have heard both in the last two weeks while demo'ing new speakers myself and they both sound really good. However, I prefer the Sonus faber sound myself. That said the fit and finish of the Olympica Nova are light years ahead aesthetically in my tastes and opinion. The Focal Kanta, though sounding awesome, have a big plastic-looking front that cheapens the look; where the Sonus faber Olympica Nova have beautiful woodwork and look like the expensive price you paid for them. That is just my opinion. If you have a more modern look in your room the Focal may be for you. They both sound great though.

Also, in full disclosure, I just bought Sonus faber and will be updating my system here when they arrive.

You have a wonderful quandary!  Enjoy the process. I am on my third Sonus faber speaker and love them ~ yet there are so many excellent speakers it is hard to not wonder what other options sound like. 
 

Honestly, it would be up to personal preference. I will say for me it would be the Olympia Nova all the way and this is coming from a Kanta 2 owner. SF standmounts sound fantastic!