The best stove I ever had was a Tilley Fold-away double burner with grill, which lasted 20 years, but they went out of business sadly some years ago.
If you are going to use electric hook up then electrical items are a better bet than gas in terms of safety. And it wont cost you anything for fuel because the price of EHU will be reflected in the pitch fee you pay per night.
We have the Campingaz Camping Chef suitcase stove and have been very happy with it. Admittedly the grill is a bit underpowered, but the hob rings are great. We currently run it off a 5g Patio Gas bottle as we already had a couple in the shed. Thinking of buying a Campingaz bottle though for next year, purely because of the size. We've stayed on a couple of sites this year where you can't take your car to the pitch and lugging a 5g gas bottle isn't great.
Alongside this, we have a Weber Go Anywhere BBQ, which we take to sites that don't have firepits. We tend to split the meals between stove and BBQ. The stove is good for whipping up a pasta dish and frying up breakfast as well as boiling the kettle. We do see lots of people using just the firepit though as their only means of cooking, but I'm not sure I could be faffed with that every time I wanted a cuppa.
------------- 2019 trips booked so far:
Easter - Red Shoot, New Forest
May - Secret Campsite, Sussex
Yes, Coleman Duel Fuel for me too. Fires up and stays lit in any conditions, robust and sturdy. Worth the money, and no messing around with hoses, cylinders etc.
As with many things, 'buy cheap, buy twice'. This is an investment!