taking or renting depends on what you need, when you are going, and how you are going -
for under 3-4 we usually take our own - it helps in the airport - between buses - getting into the parks - and getting around the resorts - especially when they are tired and sleepy - so we take our own -
in the parks - a stroller is helpful even up to 5-6 - especially in epcot - it's a lot of walking - and rest time - you can move faster and they get a rest - so they are good going in and out - but you can rent when you get there -
if you're renting - figure out how expensive it's going to be - even if it's a cheap rinky-dink stroller - it may be cheaper to bring your own and leave it there -
and if you're flying - bring the stroller up to the gate - they will gate check it - and you'll have it when you get into you stop -