Jeff Vs Jane, easily one of the most popular stories on Creepypasta, as it properly introduces Jeff's Spear Counterpart Jane. The actual fight was pretty badass, including Jane (apparently) summoning the spirits (or hallucinations) of Jeff's family to torment him. There's also this badass line.
Jeff: You missed my throat.
Every Creepypasta fans dream come true - Jeff vs Slenderman. The awesome part Jeff wins by default - Slenderman impales him on a tree but Jeff lives and cuts off Slenderman's arm, and a forest fire starts forcing Slenderman to flee, but Jeff survives that one too.