Hi Christina! Oooooooh - your trip is just a couple of weeks away, I'm so jealous!!!
Not only does my family currently drive from our house to Walt Disney World Resort, I also have a two-year-old so I've definitely been in your shoes when making this same decision. One trip we drove between our resort hotel and the parks, but our last visit my husband had the car during the day at a convention so my son and I traveled by Disney's Complimentary Resort Transportation. Honestly it's almost a toss up as to which is easier.
Disney Resort Buses are fun for small children, as well as adults who hate to drive in unfamiliar locations. You will have to fold your stroller and stow any loose items that might be hanging around. And sometimes waiting on transportation requires the use of every possible distraction you can think of. However, I do love that buses and boats and monorails drop you off steps away from the entrance, almost like a VIP.
As a resort hotel guest you'll receive a parking pass for all guest lots, so parking your car at Epcot won't cost anything extra. I like that we can drive away whenever we'd like, that we don't have to wonder if we'll miss this bus due to the long line or possibly have to stand should it be full. However when you park at a park you'll go quite a distance to the entrance. You have the option to walk, but you'll be walking a lot all day which is the absolute worst when going back to your car later. Or you can ride a parking lot tram, but you'll fold up your stroller and hold everything the same as you would had you taken a bus.
If anything, take the bus to Disney Springs as soon as you get into town as kind of like the trial run, and decide from there. I do hope you enjoy your upcoming vacation, Christina, and We'll See You Real Soon!
~Kristen