It's extremely common to find that the favored valve of the surgeon is from the company of the salesperson who has best leveraged his or her access and relationships with the cardiologist or surgeon's staff as well as with the doctor himself. Doctors don't have a great deal of time to spend with different salespeople's presentations. Staff sometimes use this to limit who even gets to see the doctor.
Sometimes staff members or hospital management (as in the case above) can have relationships with salespeople (that might or might not be lucrative) that are just as limiting as those that might be made by a not-so-ethical doctor. Hospital administrators sometime interfere because they want to work with one vendor, for simplicity or economic reasons.
One way to tell is by the statements they make. When cardiologists or surgeons are making statements that put them behind the times (such as telling an older person that tissue valves only last 5-10 years at the most), they are often being managed by a salesperson, and have used the same valve for a long time and developed a loyalty. Another is when everyone in their group, hospital, or discussion circle of professional acquaintances uses the same product, and has no interest in telling the patient about any options.
That doesn't mean they're necessarily being paid off or doing anything essentially immoral (in their viewpoint), but it can mean you don't get to "choose your poison." As you are the one who lives with the results and shortcomings of the valve, that choice may be important to you.
There are times when only one type will give the best service for a patient. However, when that happens, the surgeon is completely able to explain why that is for a particular case. That only amounts to a small percentage of cases.
The fact is that cardiologists and surgeons are as fragmented in their approaches and beliefs as the people who visit this website, and quite often more self-righteous and acrimonious in their dismissal of each other's positions as anyone in VR.com has ever gotten. Medicine has lead-butted conservatives who won't try anything new to help their patients and wild-eyed enthusiasts that are ready to plug in anything that looks shiny, regardless of whether it even makes sense. Both serve their patients badly at times. One surgeon is expert at the Ross Procedure, another at St.Jude mechanicals, another at On-X valves, and different ones for cow, pig, and (apparently) horse tissue valves. Some still use only homografts.
But most surgeons and cardiologists are somewhere in the middle, trying to make sense of all the claims.
While it can be said that you should just accept whatever valve your surgeon tells you to use, it's equally accurate to say that if you just go to a different surgeon, he will tell you he uses a different valve.
As far as efficacy, most top brand models offer the same life expectancy, so there's certainly no crime to letting your surgeon or cardiologist choose for you, if you're ambivalent to the ramifications, or just plain too petrified to choose. It's not only your choice as to which valve to use, it's even your choice as to whether to choose.
Best wishes,