I prefer food-safe sealable plastic bags such as freezer Ziploc bags. They really allow the marinade to envelop the chicken vs. a dish in which the marinade might not cover all of it.  When using a plastic bag, make sure to squeeze out excess air before sealing then roll up the bag so the chicken is nice and snug. Sealable bags are also great for easy cleanup – just toss them! You may also use food grade plastic, stainless steel, or glass containers and cover with plastic wrap if they don’t have a lid. If you marinate the boneless chicken thighs in a shallow dish, make sure to flip the chicken over occasionally so it marinates evenly.