Consider how often you need a generator in the toyhauler or for other uses. If you boondock much of the time, without hook-ups, a generator in the RV would be handy.
If most of your travel is to RV parks, you may want a portable unit that’s not mounted in the RV.
I may not get a generator in my next toyhauler. Our destinations are RV parks with full hook-ups. We’ve only used the generator once when dry camping on our farm. The Onan that is installed is more of a maintenance hassle than it’s worth, to me. I’ve needed a generator for other uses away from the RV. A portable set-up may be my next purchase.