Personally I think that a 750 Virago is a nice gentle bike afor a beginner.
Sure the weight whilst low speed riding, paddling with your feet while trying to manoeuver, could be a bit of a nuisance, but such a bike is going to be very forgiving about being in the wrong gear and the wrong revs.
Small bikes take a lot of awareness, you get knocked around by the wind, by bumps in the road, you have to get in the right gear or you make very poor progress, and the brakes are very often pretty poor.
I don’t think I’d like to ride anything much smaller than a 500, unless it was a 2-stroke lonny bike.
Talk to any biker and you’ll find they tend to have more accidents on small bikes than big ones.