Your son shouldnt have to repeat PreK4 at Eagle, they have a late bday cutoff (or used to). So that's a plus to choosing Eagle.
If your child has completed PreK4, you might want to advocate at any school for placing him at K. Depending on where he completed school (grade school vs a daycare setting), they might honor it.
The only thing I know about Leckie is lots of "Base" kids attend, which might be a bonus for you.