I think Optimum Tech has a comparison, but here are my two cents after watching many reviews of those coolers:
I would go for the L12S, if its compatible.
Stock it outperforms BR - If you run BR with dual 120noctua it will perform better, but you would need to run VLP memory.
If you run BR with 120mm slim Noctua on top, I think its very even with a small advantage to L12S - and you would have to buy an 120mm Noctua on the side.