Well lets see...
Luigi's 0-death combo ability is better, but he has bad aerial priority and a miserable time approaching, hampered by his bad short hop.
He also lacks a good projectile. His recovery is amazing but still predictable. His only good kill moves are shoryuken and up-smash, maybe down-b. Moves have average start up times. Good at edgeguarding, but pretty much any character is in this game.
Link has some pretty neat looking combos, but his ability is overall average. His aerial priority is great but he sucks at approaching, although has a great short hop. His projectile game is his bread and butter. His recovery is abysmal any way you swing it. Good kill moves include f-smash, d-smash, dair, fair and spin attack. However, this can be counteracted by his bad start-up times, and his finishers are still far from the best in the game.
Link beats Luigi face-to-face, 60:40.
Yeah, I'd put Link on top.