Size matters
In the UK mobile market
I'm with 3, purely because my partner is not ...*
That way, when we go somewhere else in the UK then a better chance at least one of us will get a signal (though have been occasions when both of us have had a not spot) to keep in touch with friends and family (as unfortunately finding a working phone box to use is quite difficult now).
It's pathetic in a country the size of the UK that coverage everywhere was not mandated, reception should not be a mobile provider lottery.
With EE getting the airwave replacement contract they are essentially getting a huge market advantage in tax payer funded coverage in less economically viable areas, consolidation of some of the other providers is about the only way to stop EE becoming a de facto monopoly.
* Neither of us with EE, tempting as it is with our liking of hiking in remote parts