Guys which wil be the best current boosting technique.......... can anyone suggest a good amplifier circuit.....?.... can an array of darlington pairs can give good efficiency?
Try to be more specific in describing what you're actually after.
If you're making a class A, B or AB, the darlington pair will about as efficient as any other driving technique. If you're making a class D, the darlington pair will be less efficient as it never saturates and therefore drops a fair voltage - transistors driven to saturation or MOSFETs will be more efficient.