Wouldn't a Moto G be a step backwards coming from a iPhone 5? Money isn't a issue I've got a spare $700 to spend for this device so if that's the only reason it's been getting recommended I honestly don't mind spending more.
It's a good step to introduce a user to Android and it's marketplace / software.
Performance is a good mid range device despite its low range price point.
Basically for £100 you could dip your toes in, see if android is for you and if not stay with iOS or look elsewhere.
So yes the 5S is a more powerful phone, but for £100 the moto g is a good dip into the android pool.