Thrusters dictate much more then just max speed and max speed while boosted.
Thrusters also dictate your maneuverability. Higher rated thrusters means a much faster Pitch/Yaw/Roll rate.
Thrusters also dictate how heavy you can make your ship. Higher rated thrusters increase how much total mass they can push allowing you to make your ship heavier without sacrificing normal space and Supercruise performance. It also increased the optimal mass which increases your speed, maneuverability, and even acceleration/deceleration responsiveness.
Jump range only matters if you're doing constant jumps.
For everything else, thrusters are by far the most important component.
D-rated thrusters may be lighter but they're also the lowest integrity which means they won't last longer then even E rated thrusters. B rated will give you highest integrity which means they'll last longer under fire, even if they're the heaviest ones. A-rated is best performance but they're power hungry.
You want to see that vanted Cutter speed and maneuverability everyone raves about? A rated or bust.