Reading these posts about Suv`s for junior and cars to accommodate all the essentials to go visit Grand-Ma makes me think how we ever managed bringing our own up, fitting the car seat, nappy bags, dropping them at sports events, take them on holidays abroad. Whether it be a Corsa, Corolla, Tiguan or what, we managed fine without child line knocking on our door.
Buy the best car you can afford, the one you like, the more money you spend, the more luxury's you will have. Its also worth noting, there are no bad cars out there these days. Apart from the small micro economy cars, all cater for isofix seats, and buggys etc. Its down to personal taste.
Tastes though, are also strange. Someone goes into a Peugeot Dealer and hands over good money for a Teepee, or that Fiat Doblo with the lights at the windscreen, I cant explain it, but someone wants it. We have also often seen the horrendous colours people choose, and say why, when they could, for the same money have chosen a "normal" popular colour.
For what its worth, your resale value on the Ateca will be awful, but then, its reflected in the purchase price.