Carbon-based nanofillers such as graphene, carbon nanotube, carbon black and nanoscale graphite are frequently used to enhance the performance for polymer nanocomposites. In this study, polystyrene (PS) and carbon-based nanofiller nanocomposites were prepared via latex technology and investigated to compare the effect of nanofiller types on rheological and electrical properties of the nanocomposites. Graphene oxide (GO) sheets, poly(styrene sulfonate)-coated reduced graphene oxide (PSS-RGO) sheets, carbon nanotubes (CNTs) and graphite nanoplatelets (GNPs) were used as model nanofillers, and their characteristics and the properties of nanocomposites were compared. GO sheets were synthesized by using the modified Hummers'' method from a commercial graphite, and PSS-RGO sheets were prepared by the reduction of GO-dispersed PSS solution with hydrazine monohydrate, whereas commercial grades were used for CNTs and GNPs without chemical treatments. Good dispersions in aqueous solution were achieved both for GO sheets and for PSS-RGO sheets, but CNTs and GNPs were able to be dispersed with the help of surfactant. GNPs were hardly dispersed because they exist in aggregate form of graphene layers. Rheological properties of PS/GO, PS/PSS-RGO and PS/CNT nanocomposites were highly increased with the inclusion of nanofillers, resulting in rheological percolation thresholds less than 1 wt% Electrically conducting pathways of PS/GO, PS/PSS-RGO, PS/CNT and PS/GNP nanocomposites were achieved at the electrical percolation threshold of 0.50, 1.01, 0.25 and 5.82 wt% of nanofillers, respectively. Among the nanofillers used in this study, PS/CNT nanocomposites showed the highest electrical conductivity and the lowest electrical percolation threshold, and on the contrary the increase of electrical conductivity of PS/GNP nanocomposites was the smallest. Both PS/GO and PS/PSS-RGO nanocomposites showed well dispersed morphology, but the electrical conductivity was better in PS/GO nanocomposites. It is speculated that the electrical conductivity PS/GO nanocomposites was further increased by the thermal reduction of GO sheets during molding. On the contrary, the PS/PSS-RGO nanocomposites showed lower electrical conductivity because the RGO portion is only half in PSS-RGO content and RGO sheets were blocked by the same amount of non-conducting PSS chains.