The inability to get a gentle simmer from gas cookers is a common problem. For one answer to this, see
here.
Best pans? Stainless steel is a poor conductor of heat. So the heat from the jets on the gas burner can produce hot-spots on a pan, since the applied heat isn't being conducted away to the rest of the pan. This can give you burned areas when you're cooking a stew, for example.
For this reason, the best pots to use are made of cast iron, or are expensive 'triple-wall', which is aluminium between two layers of stainless steel. These conduct the heat evenly from the base throughout the rest of the pan, with a much reduced chance of hot-spots.
With gas, pot shape counts too. A bellied pot will hold the flow of hot gases against the sides of the pot, again producing hot-spots. A pan with vertical sides, and a sharp edge between base and sides, allows the hot gases to break away at this edge to reduce burning.