By delegating to the 100% pool, you will accumulate twice as many GENS tokens compared to the 50% pool. In the 50% pool you are only giving away 50% of your ADA staking reward and therefore accumulate only half of the possible GENS per epoch.
DO NOT DELEGATE TO POOLS THAT ARE NOT LISTED ABOVE! THEY ARE FAKE GENS POOLS! GENS5 IS FAKE!
Do not delegate to a pool with more than 68.4 million ADA. This is considered SATURATED, and you will not earn GENS unless you delegated before the pool was saturated.