alsa or oss??
 

which is better and why??

Alsa. More mature than oss now. Free. Often updated. Oss is dyin'.

ALSA is generic at best, I use the emu10k1 driver from sourceforge
because it was written for the SB Live 5.1 card.......
ALSA can't utilize digital output very well at all.........
it's OK for analog output, but my speaker system is digital only.....

I preferred to use ALSA because its free and it works. It is very, very customizable. You can use several kinds of sound effect libraries. ALSA is OSS compatible so it should work in several programs.

imh(umble)o the one that works best is the one to use. i've had a couple of cards that just worked better w/ the oss drivers, and i've had a couple of cards that worked better w/the alsa drivers and configuration. the upside to alsa is it's the way of the future, as new cards come out, new kernel support for those cards will most likely come from alsa. hope that helps.
good luck.