I know how to analyze a circuit using Thevein's theorem, but as there are 2 voltage sources, should I solve using Superposition theorem first and then pass the resultant values into a Thevein equivalent circuit?
Or is there a more simple, easy way to do this that Im missing.
Yes. godfreyl is right. Maximum power would be transferred from RL when it is equal to R(Th) of circuit. And when you calculate R(Th), you short all independant DC voltage sources. If you analyze and solve circuit in that way, R1 and V1 have no effect on simplified circuit. Hence RL = R2 = 4 ohm.