Because we didn't want the hassle of plumbing in gas (you need a compliance certificate) or having to store it / buy it, we opted for a diesel cooktop. It takes its fuel from the main vehicle tank, so everytime you fill up with fuel, the cooking is taken care of too. We used the Webasto X100 which is pricey, but looks good and works well.
The 2010 Sprinter doesn't have an auxilary fuel line to tap into, so we dropped the tank and put in a dedicated standpipe. The cooktop comes with a filter and pump. Good information on doing this can be found here.
The insides of the cooktop, needing power and fuel inputs
The black pipe allows air into the cooktop for combustion, and the exhaust is removed by a pipe within the black one. All fumes etc stay out of the van
The exhaust pipe through the floor inside the air intake pipe. The white pipe is the fuel line
The top of the cooktop. It takes two or three minutes to get hot, and is then as quick as an electric cooktop to cook stuff