Vodafone have increased pay as you go mobile data allowances and you now get the allowance for 90days rather than 30.
Sim is advertised as for iPad, but I don't see why it would not work in any other tablet/dongle device.
So for £25 you get 15GB 4G data to use in your mobile data device over 90 Days.
O2 offer a 90day tariff at £25 but you only get 5GB of data.
I'm struggling to find any information on the EE site with their offer.