I have tried Nikkor 65/4 Rodenstock 65/4.5 and Schneider 65/5,6. All of them perform great. I have the Rodenstock because it was the cheapest with the centerfilter included, and came factory mounted in a Sinar board. Mine is Sinaron branded.
I my case, I need centerfilter. If you shot landscapes, you maybe do not need a centerfilter, and in that case I suggest you to buy the cheapest you find.