I often am asked how I choose which Lav mic I am going to use in a situation since I have Sanken Cos-11 and Countryman B6.
The Sanken is my first choice for almost all situations it is easy to hide and I think provide the best match to my Primary boom mics which are MKH 50 and the Scheops Cmit 5U. It is durable and very easy to wind proof.
The Countryman B6 is best suited for hard to hide in wardrobe, wet situations and if we are doing many wardrobe changes like on a crime reenactment show that might have 6-8 changes a day. The B6 doesn’t sound as full as the Sanken but sometimes it is the best choice.