OE-quality thermostats from OE-manufacturers offer good value for money when the only difference is the presence of the car manufacturer logo. f.ex. the BMW M54 thermostat is made by Beru, which is the brand offered for this engine here too.
Mishimoto racing thermostats as well as originals are available. We recommend Mishimoto for tuned engines, and OEM-level thermostats for everyday cars.