Well most of the people suggesting are mostly just suggesting based on their own preferences, while I would suggest you to buy a car out of your own requirements. I have owned both cars and will try to give you an honest suggestion.
Yaris and Grande are almost equally comfortable for the driver, if you regularly travel with five people on board, grande provides more space, with four people onboard grande has no specific space advantage.
Power and pickup for mature driving is fine for both cars. Both have CVT and give quite a decent drive. Yaris gives much better fuel economy while Grande is more powerful.
With Grande you get extras like Sunroof, Cruise Control, Padal Shifter etc. but i don't consider these worthy of paying a million extra for...
Grande is bigger in size, bigger wheel-base makes it slightly more comfortable but at the same time maneuvering is easier in Yaris within city, its smaller size is very convenient for driving it in narrow streets and in bumper to bumper traffic.
Yaris Can be parked considerably easily even inside narrow garages, a friend sold his corolla and switched to Yaris for this very reason, he had a smaller garage and was hard to get out of the car after parking it indoors... Yaris solved is problem...
One huge drawback with Corolla is safety and security, its a favorite car for thieves, its a headache for owners, you stay very conscious and worried... insurance and tracking devices and there but then again its a hassle getting claims... you are never peaceful with a corolla, be it parked outside your office, home or in a market... you always have a theft scare at the back of your mind. With Yaris, you don't need to worry alot about its theft, hardly heard of any yet...
Yaris has a drawback, while its almost like a corolla, but with a sudden passing over a speed breaker without slowing down, you do hear a 'dung' sound... which hurts in the beginning but you get used to of it. The door trims are also not as sturdy as Corolla, but if you don't compare them, they are fine.
Another down side with Ativ X is that the sound system is not android, although it can mirror your phone screen with an app called TLink and you also get touch screen support but its not as operational as a proper Android would have been. The audio quality is good being a KenwoodJVC system but screen is small and non-Android. Although i don't like watching videos while driving but you feel deficient
and remain phone dependent for Navigation etc.
As for suggesting a car amongst the two, buy what you need instead of getting a used car, I would suggest that if you don't travel frequently with 5 people on board, get Yaris... its a good car with almost a million less on your pocket.
If you frequently need to drive with 5 people, get Grande.
