We rented last time for kids 2 1/2 and 3 1/2 and will rent again this time for kids 4 and 5. I didn't regret it, but reading these threads, have come up with some things to think about:
1) Do you really like your own stroller? (we don't, we barely use a stroller at home - never any longer)
2) Does you child still fit comfortably in your stroller (my 3 1/2 year old didn't).
3) Is your child older? (Disney strollers are NOT good for infants, and I think bring your own is pretty good blanket advice for most kids until they are about two. However, Disney strollers are great for four and five year olds that won't fit in a traditional stroller)
4) Are you planning on doing DTD or someplace else
stroller rentals aren't available? Are you anticpating a long walk to the room? (We don't do DTD. We have to get from our room to Disney transportation, from transportation to the parks, and back. Ususally carry-able.)
5) Is your child a "good walker?" My son could run marathons and can walk endlessly. We might need to carry him a little at the end of a long day. My daughter is not a good walker. She is slow and gets tired more easily, and really wants to be carried all the time.
6) Are you counting on stroller naps? Its possible to sleep in a Disney stroller, but especially for little ones that can fit well in a reclining stroller, your own will be more comfortable. (My kids are big enough were they'd nap better in a Disney stroller).
7) Can you lift your child easily in and out of the stroller? My 2 1/2 year old could get into the Disney stroller herself, buckle herself in, and when we stopped, unbuckle herself and get herself out. Saved a lot on mom and dad's backs (so that we could use those backs to carry her back to the hotel).
8) Does your stroller fold easily? Will you have enough hands to handle child and siblings, stroller, diaper bag etc. on and off the buses? In some cases it may be easier to rent and carry a child a short distance than to deal with child, stroller, and stuff.