Scooter ideas for a 5 year old

Hi all

My son turns 5 shortly and wants a scooter.  Would I be best getting him a 2 wheeled one which will probably last until he's quite a bit older or a 3 wheeled one which he may feel safer on at first but is likeley to grow out of sooner?

Also, any ideas for ones to try? Ideally, I'd like a folding one as we travel by bus a lot...

Thanks

XXX