My first vote would go to Swiss Arms, if it were an option, but of the two you mentioned, I'd go with the Tavor. Canada Ammo backs up his products and love it or hate it, the Tavor is built to serve as an actual combat rifle. The XCR remains the almost-ran, bridesmaid in that department.
Also, I try to avoid any rifle that requires 200+ rounds of factory ammo to 'break it in' before I can expect reliable functioning, and I also avoid any factory rifle that requires me to loc-tite parts to keep them from falling off.
Getting to be a 'Beta' tester for Rob Arms' previous rifle, the M-96, and like so many others, drawn in by the promise of a top mag feed for the same (which never materialized) and then finding the company totally dropping the rifle model and their owners, left a sour taste in my mouth.
Added to that the recent rant by Rob Arms president, Alex Robinson, making the Internet forum rounds and I'd avoid the XCR like the plague.