The single-leg Romanian Dead Lift
 

Balance is required for the single-leg Romainian Dead Lift, and when loaded, you can feel so many fibers firing to stay balanced. The "hypertrophy-bros" will argue that this does not strain the muscle properly, however this is done in conjunction to hard RDL's or another posterior-based action.

Training unilaterally activates the core and aids in the correction of muscle imbalances. This will not only make you a better and healthier person, but it will also help you improve in other lifts.

https://www.youtube.com/watch?v=ffx7vhpocAc&t=2s