Which Roomba should first-time buyers get to avoid disasters?

The [Roomba j](https://www.amazon.com/s?k=Roomba+j&tag=wehavethat-20)7+ is the one for first-time buyers — it avoids disasters with its obstacle avoidance that won’t chew through phone chargers, eat socks, or redecorate with pet waste. Roomba is so confident they offer a P.O.O.P. warranty (Pet Owner Official Promise) that replaces the robot if it fails, but you probably won’t need it because the avoidance actually works.