I think Lucas is a lot better, his tilts and smashes combo from his air moves (I don't get how people can think Ness is better at it, have you seen Lucas' dair and nair? Incredible.) His bair can even combo to his ground moves, I got a jab lock the second time I tried playing as him. His forward smash is insane, it comes out really fast and it killed me from the center of Battlefield at 94%. People say his up smash sucks, it's like one of the best in the game, G&W's is considered way over-powered, but Lucas' is just a couple frames slower, but it has much better range, great priority and it's like an upwards Falcon Punch. His upsmash is great, Lucas' down smash does huge damage at low percents because it scores more than one hit, it has good power at high percents and it is unsafe to be hitwith on both block and spot dodge because of it's lingering hit box and it eats shields. None of his smashes can be punished after shielding, and his smashes will hit even if you spot-dodge with the exception of forward smash which is difficult if not impossible to punish after spot-dodging it.
People also say his air game sucks, when it is actually very good, both his dair and bair meteor and Lucas' dair is more reliable as both a meteor smash and a normal attack, which can also be used to approach btw. His fair is not bad at all and actually seems to have good range and power, his uair is pretty good too as it connects easily out of his second jump. I don't even have to tell you how good his nair is, it does good damage, range, lingering hitbox, and combos into a lot of moves. His dair will even chain into his upsmash, that's insane. Everyone knows how good his standard ground game is, so I'll move into his camp game.
Lucas' PK Fire does more damage and pushes people away, Ness' can be DI'd easily. Lucas' PK Thunder also has more potential for damage than Ness' because it can loop. Lucas' down b is better as well because it protects him on both sides and it can actually kill. Ness' backthrow is better, but the rest are not as good as Lucas' and Lucas can kill with his as well, but Ness' backthrow is stonger. Lucas also has a jab that comes out in two frames. I don't need to tell anyone how much better of a recovery Lucas has than Ness.
Lucas' edgeguarding game is better because his nair can chain to his dair and his nair brings people down with him. His bair and dair are meteorsmash, which are good for edgeguarding and his PK Thunder pushes people away. Also, up smash while edgeguarding is great.
Statistically, he is also faster than Ness both on the air and on the ground, however I prefer to use Ness.