Currently it's looking like GiffGaff have the 'best' plans in place to replace Three. £15/month for 5GB data all of which can be used for tethering or £18/month.. for unlimited data and no tethering at all.
Still a fair bit better than Three's pricing (hell, you can get an unlimited data sim for your phone and a 5GB data sim for a spare phone to use for tethering, and it'll still only be £5/month more expensive than Three's current offerings @ £28 for unlimited everything & 4GB tethering on monthly rolling!)
Are they any good for data these days?