If budget allowed I'd stay at a monorail resort for convenience in getting to MK, but we recently stayed at All Star Sports and our toddler and preschooler LOVED it! They absolutely loved the baby pool, playing around the big football icons, etc. and the food court had plenty of little-kid-friendly foods. The room was small but quite adequate, and our toddler just went nuts for the star-shaped lights above the bed! Monorail would've been really nice (great to be able to roll the stroller right on instead of having to fold it and carry it) but the bus service was just fine.
Next time if we can get a good discount we'll stay at a monorail resort, but if not we'll be more than happy with the All Stars or at Pop Century (which has a fountain that I know my tots would love to play in!).
I don't think you can go wrong. Have a great trip!