RP synchromax.
I've been using it for five years now and about 20k miles
It has stood up well.
I'll be changing it this year and will use the same again.
Generally smoother shifting than the OE fluid.
Old RP discussion here...
http://www.zpost.com/forums/showthread.php?t=626963
I should add, that I have experienced other mt cars that were VERY sensitive to the type of oil used.
The worst was a G35 that I changed to Redline.
Soon as I got out of the driveway I knew it wasn't going to work.
Swapped the OE fluids back right away.