Light and L have a fascinating dynamic. Their cat-and-mouse (or cat-and-cat?) relationship is the core of Death Note, and, although the decision to kill L partway through is bold and interesting, the series never quite recovers from his loss.
Although they're enemies, Light connects with L on a level he's not used to with his peers. L is infuriating, but he's also refreshing; he's someone Light can see as an equal, and I don't think Light has ever felt anyone could face him on even ground before.
When I saw the Death Note musical on stage, there was a great little moment for Light and L's dynamic just after their intense, furious tennis duet. Light won the match and hurled his racquet viciously across the stage in victory. L picked it up, held it out to him and said, 'I enjoy our time together.' Light stared at him for a long moment before accepting the racquet and saying, grudgingly, '...yeah, me too.'
In the Death Note musical track 'The Way It Ends', Light is triumphant over L's imminent death, but you can hear him go from mocking to wistful in the final line, as it hits him that L's death is a loss to him as well as a victory, and it's absolutely agonising.
L absolutely drives Light up the wall in every scene they have together, and it's a delight! But, on some level, Light is enjoying himself. It adds such interesting depth to their antagonistic relationship.