From what I have heard, there is some dark magic involved with disk cache layout; A lot of things affect performance: Too much in the cache, too little in the cache, underlying filesystem layout, file system size, filesystem type, disk hardware, disk placement (front of the disk vs end of the disk), other items on the same disk controller, other general hardware items, etc, etc.
I'm not sure any one choice would be better for everybody long-term, but ufs may be the best place to start.