The thing about prescribed medicines is that they are highly regulated and made to set standards. To all intents and purposes who made a medicine is unimportant to the consumer provided it is obtained through a pharmacy here in the UK. They are all the same. If you live in a country without those regulations or if you want to take pot luck and buy from unregulated sources, then things might be different and only then thinking about the manufacturer might have some relevance.
That said, I am sure if you talk to a pharmacist they will have preferred manufacturers but that will have little to do with quality. It will be all to do with how reliable they are as suppliers and how much they charge. They would not go near any manufacturer they thought was not manufacturing to the required standard.