After renting a car a few trips back, we have since always rented one. We also like the freedom of being in control of our own transportation, and with 3 kids and a stroller, it’s a lot easier to load/unload. DH hates taking the stroller on the busses. As was also previously said, we get the AAA Diamond parking voucher, which keeps us close to the park entrance.
When I was price comparing for our trip a few weeks ago, I found that one week the Disney Car Care Center was more expensive, one week it was the same, and then another week it was cheaper. I think you just have to check and compare (& check back) to find the best deal. But it’s definitely not always more expensive. I actually had it booked there the week that I found it was cheaper, but we ended up flying into Tampa to visit family first for a couple of days, so we picked up the car in Tampa.