I'm desperate to get away from 3. Over the past few months I have had very poor download speeds on 4g at different locations. Sometimes despite good signal strength their network is unusable. I have a
mifi on EE as a backup which is seeing increasing use.
I plan to change my phone to Popit (EE) and my
mifi to Asda Mobile (Vodafone).
Asda Mobile have an offer at the moment with double the data allowance for the same monthly payment. This will continue as long as your monthly payment continues. Well worth a look.