You're probably best off with Renzo Gracie's for leg locks. John Danaher, Garry Tonon, and Eddie Cummings are all regulars there.
Marcelo's will bring you the best all around jitz, in my opinion. 50% gi 50% no gi is their thing and it's all about jiu jitsu. No mma. Renzo's has mma on top of jiu jitsu. If you're explicitly looking for no-gi and leg-locks, Renzo's is an easy choice.