Space industry across the globe is currently undergoing revolutionary changes triggered by the success of private space agencies like SpaceX and Rocket Labs. Rocket configuration and design philosophies that have been faithfully followed till date are under scrutiny and novel concepts are being proposed to build rocket systems which are both cost effective and reliable. One such novel thought is to use rocket engine cycle where propellant pumps are powered by Brush-Less DC (BLDC) motors instead of the conventional thermodynamic cycles. Though the idea of having electric pumps in rocket engines seems attractive in a global perspective, detailed study shows that the concept is limited mainly by the powers to which the BLDC motor, the associated electronics and harnesses can be practically designed. These considerations seriously limit the usability of this novel rocket engine cycle. Careful selection of propellant combination to meet the mission requirements of a rocket upper stage while still allowing for practical engine design seemed a challenging task. The present paper details the study done in this regard through a comparative study on suitability of four propellant combinations, including historically used (N₂O₄-UDMH, N₂O₄-MMH & LOX-RP1) and novel (LOX-LCH₄) propellant combinations. The study is aimed at obtaining a realisable limit of thrust and chamber pressure for electric pump fed engine running on each propellant combination under consideration with the constraints on motor power and derive the payload benefit in comparison to conventional rocket configuration used as reference.