This article presents performance comparison between different liquid metal-based nanofluids termed as nano-liquid metal fluids in a microchannel heat sink to achieve ultimate cooling solutions without sacrificing the compact structure and heavy computing speed. The hydraulic and thermal performance of nanofluids having five different liquid metals (Ga, GaIn, EGaIn, GaSn, and EGaInSn) as base fluid and four different nanoparticles (carbon nanotube (CNT), Al2O3, Cu, and diamond) as solute are evaluated comparing with water-based nanofluids. Three-dimensional flow inside miniaturized channels are predicted using single-phase and two-phase numerical simulations. Numerical models are validated against data obtained from experimental studies from the literature. Three different grids are developed, and several element sizes were compared to obtain the grid independence. Upon evaluation, the study can point out that liquid metal-based nanofluids can generate much superior heat transport characteristics with more than 3.41 times higher heat transfer coefficient compared to conventional water-based nanofluids. GaIn–CNT combination exhibits the best thermal solution possible with a heat transfer coefficient increment of 2.68%, 17.19%, 22.16%, and 2.62% over CNT particle-based EGaIn, EGaInSn, Ga, GaSn liquid metal, respectively, for Re = 750. Considering hydraulic performance, performance evaluation criterion (PEC) has been introduced and Ga-based nanofluids are found to be most effective in this perspective. The effect on overall cooling effectiveness has also been carried out with a detailed particle concentration study. This study paves the pathway of using these extraordinary coolants in mini/microchannel heat sinks.