I'm no expert in tournedos rossini, but I had La Sirene's delicious version last weekend - it was rich, smooth, and the beef was cooked to a perfect medium rare. My fiancee and I really enjoyed dinner sitting at La Sirene (and their BYO policy).
I had it last night at Le Philosophe. Cant compare it against the rest but I thought it was delicious. Not super big but just the right size to be able to share. perfectly cooked filet medium rare. Super rich Madeira sauce, didn't care much for the foie.