My observations of recently moving from an extended to crew cab:
1. Larger bulky items will fit better in an extended cab where there is no pillar between the front and rear seats and the rear doors are hinged to the back.
2. The extra amount of extra space to haul gear is surprising in crew verses extended.
3. It is more convenient to access items in the back with crew doors than having to open front and rear extended cab doors each time.
I have owned one standard cab truck and would not go back to one due to the lack of seat comfort and interior storage. My first extended cab truck had no rear doors - This was fine in my youth, but the access is about as good as a coupe with a back seat. My second extended cab had suicide doors on both sides - This works well for access but leaves back passengers trapped until the front door is open. My current truck has a crew cab making access much easier to the rear as long as items fit through the door opening.
Although I have not had the crew cab very long, I feel the extended cab is the best compromise for overall length and extra cab capacity. If my Ram was offered with a Super Cab like my previous Ford, I would have chosen it over the crew. Ram's Quad Cab in the smaller trucks (their version of the extended cab), reduces the rear door openings too much for my use. GM's extended cab works just as well or better than Ford's, but the cab is shorter in height and can be a head banger for taller people.