good front forks

[LangersGT]

i have a 1997 GT Zaskar and have been looking at front forks i believe mine a 1998 model (as mine is a late oct 97) so would of come with rock shox SL?? My question is is what are some good alternatives?? and what is the different levels i.e is rock shox sid top of the range?? my mate runs manitou SXR these good is there anything better these dont have lock out

any help i would be most gratful

regards

Langers