To be honest the normal alum compared to the "lightest" alum will only differ in an ounce or two so I wouldn't recommend going for a super light one as we have seen some lightweight sprockets completely break apart at their core (not teeth, but the core of the sprocket) due to being too light.
I would recommend the Driven Racing alum rear as they are great quality. Renthal and AFAM are also great alum sprockets, but they are imported so if you have an issue you won't get the level of service that you can get from Driven. That is the only edge Driven has over the other two. They also have a more modern anodizing process which allows them to have a black sprocket.
If you want super lightweight then I would recommend the DID ERV3 with an alum rear. Just realize if it's on a 1000cc bike you won't get much support from DID should something happen. However, the sprocket will be the weak link in the set up so it shouldn't be an issue at all. The one nice thing about having the sprocket be the weak link in the chain kit (vs the chain the weak link with a steel rear sprocket) is that it's better to sheer the teeth of the sprocket should something fail compared to having the chain break and take out your engine, swingarm, foot, rearsets, etc.
You can save money by getting the ek mvxz or rk gxw chain which is stronger (not relevant with an alum rear sprocket), but more importantly it's less expensive and only ounces more weight. You won't notice ounces of rotational mass, but if you want the lightest set up then the alum rear with did erv3 would be it.
I run alum rear with ek mvxz chain and clean/lube my chain kit all the time and my last rear sprocket lasted me nearly 15k miles. Maintenance is the #1 factor in the life of a chain kit