Hi Mike
I've had a motorcycle, currently two, that I have used since I was 14. I'm 66.
I have a BMW K1200RS and a Yamaha FJR1300A.
I raced D-37 (Southern CA) desert from 1964 to 1975. I now prefer street riding.
I prefer the liquid cooled engines to the air & oil cooler engines for their longevity. This is not to diss the air heads and the oil heads, as they are excellent engines, it's just my preference.
Now to the GS. The GS is NOT a dual sport bike. It can be ridden on a dirt road, as can any street bike, but is in NO WAY a suitable dirt machine.
I spend my retirement riding to BMW Rallies and the GS is a popular bike, used mainly for street riding. I has a high center of gravity, a high seat height and a long wheel base... . which makes slow speed (parking lot) maneuvers difficult..... especially for inexperienced riders.
You do not say if this is your first bike or if you have been absent from riding for some time. If so you MUST take a beginning rider's course from the Motorcycle Safety Foundation. Techniques do change over the years. I would not consider the GS a suitable bike for a beginner or for someone absent from riding for a long time.
As to the Yamaha and the BMW... . I wanted to try the darling of the Iron Butt Riders, the FJR, and have found it to be a very excellent bike. There are things I like and dislike about each, but I find myself riding the FJR more than the BMW. I prefer the low speed handling of the FJR, but the BMW is definately smoother, high speed is a push.
There just isn't any one machine that can do everything well..... especially dual sports... they are loaded with design compromises.
HTH