Years back (prior to 2001) as a beginner rider who’s only moto riding experience was 250cc MSF training bike for a few hours.
I travelled overseas to Switzerland. I rented moto for 3 days from Nice, France. The only motos they had available was giant BMW GS or Ducati Monster. I was 5’10” 130 lb., I felt more comfortable on the Monster than the GS. so I rode it through the French/Swiss Alps. It’s a great handling bike, lightweight, and good seat height (for me). Throttle responce can be snatchy, just avoid grabbing a handlful of throttle at all cost.
In the twisties mountain passes in the Alps, the Monster was a great moto… after that experience, I was 80% ready to ride any moto, as if I tamed the wild Italian stalion, I remember I rode a yellow Monster..
If you have a choice, start with the less expensive moto to gain experience, or you could just rent one and buy all the insurance to cover for any mishalp. Monster 750 is not as good of a “beginner moto” as a Ninja 650R, but it is a better bike overall IMO. Just make sure the carbs on that Monster are clean, sync’ed and balanced well.