First post so be nice etc. Not seen it posted either, so here goes!
I'm already with 3 and due for an upgrade on my current SIMO contract (exact same one but paid 1/2 price for 3 months then £17pm) Saw this on the Wuntu app and thought it was stonkingly good considering they've now upped the price to £19pm so you save £84 a year (£7 x 12)
Perfect for me as I use data a lot and hardly any minutes, plus they let you use up to 12GB for wifi hotspot. Never has problems with 3 customer service personally and their Feel At Home package is awesome (used my 12GB data in Italy on vacay last year for free!)
Only shame is no Quidco - they do £50 cashback for 3 but only for new customers on 12m SIMO with data >4GB and excluding special offers so I'm assuming it includes deals on Wuntu