I've stayed at AS Sports, AS Music, Pop, POFQ, PORS, CSR, CBR, WL, AKL, and BW. Where I stay depends on what I'm doing that particular trip (how much time I'm going to be at the resort) and also on what discount codes are available during that time. I'm helping a coworker plan his first ever trip to WDW right now. I asked him how much time he planned on spending on different activities (at the resorts, at the parks, eating, at the water parks, at DTD, renting water craft, etc). After talking with him I recommended they stay at POP and do the basic
DDP with seven day base tickets. He definitely wanted a dining plan, had no problem not being able to park hop park, and agreed that they wouldn't be in the room enough to really enjoy a moderate. They just needed a place to crash at night.
For me the difference is:
Moderates have bigger rooms, fridges, ceiling fans, covered bus stops, boat to DTD (at POFQ and PORS), queen size beds (at CSR), health club/spa (at CSR), lounges, pool slides, better themed pools, hot tubs, TS restaurants (except POFQ), more restful/peaceful, better theming (less concrete and more landscaping), and are less noisy. They also all have double sinks in the restrooms (except CSR).
I like the moderates and my last several stays have been at moderates. I'll also be in a moderate for my upcoming Sept/Oct and Dec trips, but I also have no problem staying at a Value and enjoy the trips where I do stay at a Value. I'm just not in the room or around the resort as much.