Let’s assume the quality and reliability are the same just to take that out of the decision process.
Go to any marina and count the motors on the back of boats and you will find Yamaha is 7 out of every ten motors.
So…. when it comes time to sell obviously 7 out of 10 buyers* are looking for that Yamaha motor hence faster time to sale and a better price.
In about the same area there are only 8 Suzuki dealers to over 100 Yamaha dealers.
There are several other reasons boat buyers pick Yamaha Outboards 7 out of 10 over all others combined.
Yes Suzuki is a less expensive motor. The 300 hp is about 3800 bucks less than the Yamaha BUT think Reliability, Service Availability, Resale value and I am sure you also will come to the same conclusion.