Smiths as a company I dont really know their product, but a few basics……ignore any manufacturer bullshit about strength and UV protection when/if looking at polycarb lenses they are ALL 100% UV it has nothing to do with the manufacturer its an inherent property of the material, similarly any strength difference will be down to thickness of lens for the same reason.
The optical differences are down to the tints/polarisations and coatings that are then applied to the lens.
Take there into account and within the industry Maui Jim are recognised to be second to none with Serengeti a close second, a few of the others including adidas and Nike also get good reviews. their lead over other brands……pretty small percentages per pounnd tbh. Saying all this I have 2 pairs of Oakley,2 addida 1 nike, 3 maui and a couple of pairs of bolle oh and one of police………for me the Maui’s win every time