Samshield without a doubt! I received my second Samshield this Friday. Can't imagine riding with anything else (I've been using Samshield for 3/4 years)
I would say I like Charles Owens are better but it just depends on your own head shape and how you like it. I would try both on before choosing the one you like.
Samshields are more convinient because you can take out the inside and throw it in the wash! Also they have the matte which is rain proof and you can clean it off easily. They also look flattering on many people and have the attachable visor and the miss shield!
Samsheilds. They are more flattering to me and fit my head better. But it really depends on what fits you the best.