I note that B&H has both the Lexar 64GB XQD Professional 1100x Memory Card, and the Lexar 32GB XQD Professional 1100x Memory Card for sale now. The 64GB version is $155 more than the Sony 64GB Series S Card, and the 32GB version is $30 more than the Sony 32GB Series S Card.
Both essentially run at the same speed, though the Sony is rated at about 8.3% faster in writing. In my D4, I couldn't successfully measure the difference, but with the Sony XQD cards being less expensive, I see no reason to purchase the Lexar cards at this time.
The more popular 32GB cards from both manufacturers are backordered at this time, but the larger 64GB cards are both in stock.
The Lexar XQD cards are not yet available at Adorama at this point, but I'm sure they will be in the future. The Sony XQD cards are available there. Both Sony cards are quite a bit more expensive at Adorama.