Personally, I think kids are better having Saturday off, because then they get two whole days to see their friends, go out with family and just... be kids!
Even the games consoles that they play may not be educational as such, but they do help develop reflexes and hand/eye co-ordination.
To me, if kids had Wednesdays off, that would provide them with just one day to have fun during the week, and then they are back in the classroom... two days feels like more of a break, one day doesn't.
Another reason is that kids generally start to wind down on a Friday afternoon and are not great first thing on a Monday. If they have their days off spaced out, they will be winding down twice a week and tired and unwilling twice more.
I guess there is an argument in favour of both scenarios, but this is how I see it. I hope that helps.