Stability control and traction control don't come into use when cruising on highways or other normal driving conditions. They only come into action when the car will be losing control, like if some tyres are moving faster than the others etc. This generally happens when tyres lose contact with the road or the car starts slipping sideways. It just applies selective braking to control understeer or oversteer. So, issues created by a raised height, like, the floating feeling etc, will remain there even in cars with stability control and traction control.
A Corolla is wider and longer, its tyre tread is greater, and it has a longer wheelbase. It is bound to feel more stable on the road. That is simple science. It is a different segment of car compared to a Yaris. If you want a more stable ride, you should choose the Corolla. If you want a more cost effective ride, or more features, you should choose a Yaris. You won't compare a City with a Civic, would you? A Civic is always going to be more stable. Same is the case here.
