5 GHz will have less interference, less range too I suspect.
If by "range" you mean the furthest it can go, there's not a lot in it with any of them. Fixed Tx power, fixed physics, same receiver sensitivity. You might get more sped at a given range closer in, but not at the limit of reception.
MaxDSL - goes as fast as it can and doesn't read the line checker first.
Are your kids pirates ? Limewire, Bearshare, Kazaa, BitTorrent, eMule are all tools of the trade.