Thanks everyone for your feedback, that's really helpful.
We've taken the plunge and booked with Family Ski today and are really looking forward to it
. Although both companies look very similar, Family Ski seemed better suited to cater for what will then be our almost 4 year old daughter in terms of skiing and we preferred the flexibility in being able to book our own flights but having the transfer included.
We also loved the idea that they have a ski school helper who stays with the youngest ones/beginners while they are at ESF ski school so at least they are with someone familiar who can help when we're not there.